Added robust primitive cubic/quadratic/linear equation solutions.

Applied to eigen-value calculations. Fixed repeated-eigen-value issues
in eigen-vector generation.

applications/test/cubicEqn/Make/files

@@ -0,0 +1,3 @@
+Test-cubicEqn.C
+
+EXE = $(FOAM_USER_APPBIN)/Test-cubicEqn

applications/test/cubicEqn/Make/options

@@ -0,0 +1,3 @@
+EXE_INC =
+
+EXE_LIBS =

applications/test/cubicEqn/Test-cubicEqn.C

@@ -0,0 +1,101 @@
+#include <ctime>
+#include <random>
+
+#include "cubicEqn.H"
+#include "IOstreams.H"
+#include "stringList.H"
+
+using namespace Foam;
+
+scalar randomScalar(const scalar min, const scalar max)
+{
+    static_assert
+    (
+        sizeof(long) == sizeof(scalar),
+        "Scalar and long are not the same size"
+    );
+    static std::default_random_engine generator(std::time(0));
+    static std::uniform_int_distribution<long>
+        distribution
+        (
+            std::numeric_limits<long>::min(),
+            std::numeric_limits<long>::max()
+        );
+    scalar x;
+    do
+    {
+        long i = distribution(generator);
+        x = reinterpret_cast<scalar&>(i);
+    }
+    while (min > mag(x) || mag(x) > max || !std::isfinite(x));
+    return x;
+};
+
+template <class Type>
+void test(const Type& polynomialEqn, const scalar tol)
+{
+    Roots<Type::nComponents - 1> r = polynomialEqn.roots();
+
+    const scalar nan = std::numeric_limits<scalar>::quiet_NaN();
+    const scalar inf = std::numeric_limits<scalar>::infinity();
+
+    FixedList<label, Type::nComponents - 1> t;
+    FixedList<scalar, Type::nComponents - 1> v(nan);
+    FixedList<scalar, Type::nComponents - 1> e(nan);
+    bool ok = true;
+    forAll(r, i)
+    {
+        t[i] = r.type(i);
+        switch (t[i])
+        {
+            case roots::real:
+                v[i] = polynomialEqn.value(r[i]);
+                e[i] = polynomialEqn.error(r[i]);
+                ok = ok && mag(v[i]) < tol*mag(e[i]);
+                break;
+            case roots::posInf:
+                v[i] = + inf;
+                e[i] = nan;
+                break;
+            case roots::negInf:
+                v[i] = - inf;
+                e[i] = nan;
+                break;
+            default:
+                v[i] = e[i] = nan;
+                break;
+        }
+    }
+
+    if (!ok)
+    {
+        Info<< "Coeffs: " << polynomialEqn << endl
+            << " Types: " << t << endl
+            << " Roots: " << r << endl
+            << "Values: " << v << endl
+            << "Errors: " << e << endl << endl;
+    }
+}
+
+int main()
+{
+    const int nTests = 1000000;
+    for (int t = 0; t < nTests; ++ t)
+    {
+        test
+        (
+            cubicEqn
+            (
+                randomScalar(1e-50, 1e+50),
+                randomScalar(1e-50, 1e+50),
+                randomScalar(1e-50, 1e+50),
+                randomScalar(1e-50, 1e+50)
+            ),
+            100
+        );
+    }
+
+    Info << nTests << " cubics tested" << endl;
+
+    return 0;
+}

src/OpenFOAM/Make/files

@@ -125,6 +125,9 @@ $(spatialVectorAlgebra)/SpatialVector/spatialVector/spatialVector.C
 $(spatialVectorAlgebra)/SpatialTensor/spatialTensor/spatialTensor.C
 $(spatialVectorAlgebra)/CompactSpatialTensor/compactSpatialTensor/compactSpatialTensor.C
 
+primitives/polynomialEqns/cubicEqn/cubicEqn.C
+primitives/polynomialEqns/quadraticEqn/quadraticEqn.C
+
 containers/HashTables/HashTable/HashTableCore.C
 containers/HashTables/StaticHashTable/StaticHashTableCore.C
 containers/Lists/SortableList/ParSortableListName.C

src/OpenFOAM/primitives/Tensor/tensor/tensor.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2017 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -24,6 +24,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "tensor.H"
+#include "cubicEqn.H"
 #include "mathematicalConstants.H"
 
 using namespace Foam::constant::mathematical;
@@ -72,137 +73,76 @@ const Foam::tensor Foam::tensor::I
 
 Foam::vector Foam::eigenValues(const tensor& t)
 {
-    // The eigenvalues
-    scalar i, ii, iii;
+    // Coefficients of the characteristic cubic polynomial (a = 1)
+    const scalar b =
+      - t.xx() - t.yy() - t.zz();
+    const scalar c =
+        t.xx()*t.yy() + t.xx()*t.zz() + t.yy()*t.zz()
+      - t.xy()*t.yx() - t.yz()*t.zy() - t.zx()*t.xz();
+    const scalar d =
+      - t.xx()*t.yy()*t.zz()
+      - t.xy()*t.yz()*t.zx() - t.xz()*t.zy()*t.yx()
+      + t.xx()*t.yz()*t.zy() + t.yy()*t.zx()*t.xz() + t.zz()*t.xy()*t.yx();
 
-    // diagonal matrix
-    if
-    (
-        (
-            mag(t.xy()) + mag(t.xz()) + mag(t.yx())
-            + mag(t.yz()) + mag(t.zx()) + mag(t.zy())
-        )
-        < SMALL
-    )
+    // Solve
+    Roots<3> roots = cubicEqn(1, b, c, d).roots();
+
+    // Check the root types
+    vector lambda = vector::zero;
+    forAll(roots, i)
     {
-        i = t.xx();
-        ii = t.yy();
-        iii = t.zz();
-    }
-
-    // non-diagonal matrix
-    else
-    {
-        // Coefficients of the characteristic polynmial
-        // x^3 + a*x^2 + b*x + c = 0
-        scalar a =
-           - t.xx() - t.yy() - t.zz();
-
-        scalar b =
-            t.xx()*t.yy() + t.xx()*t.zz() + t.yy()*t.zz()
-          - t.xy()*t.yx() - t.yz()*t.zy() - t.zx()*t.xz();
-
-        scalar c =
-          - t.xx()*t.yy()*t.zz()
-          - t.xy()*t.yz()*t.zx() - t.xz()*t.zy()*t.yx()
-          + t.xx()*t.yz()*t.zy() + t.yy()*t.zx()*t.xz() + t.zz()*t.xy()*t.yx();
-
-        // Auxillary variables
-        scalar aBy3 = a/3;
-
-        scalar P = (a*a - 3*b)/9; // == -p_wikipedia/3
-        scalar PPP = P*P*P;
-
-        scalar Q = (2*a*a*a - 9*a*b + 27*c)/54; // == q_wikipedia/2
-        scalar QQ = Q*Q;
-
-        // Three identical roots
-        if (mag(P) < SMALL && mag(Q) < SMALL)
+        switch (roots.type(i))
         {
-            return vector(- aBy3, - aBy3, - aBy3);
-        }
-
-        // Two identical roots and one distinct root
-        else if (mag(QQ) > SMALL && mag(PPP/QQ - 1) < SMALL)
-        {
-            scalar sqrtP = sqrt(P);
-            scalar signQ = sign(Q);
-
-            i = ii = signQ*sqrtP - aBy3;
-            iii = - 2*signQ*sqrtP - aBy3;
-        }
-
-        // Three distinct roots
-        else if (PPP > QQ)
-        {
-            scalar sqrtP = sqrt(P);
-            scalar value = cos(acos(Q/sqrt(PPP))/3);
-            scalar delta = sqrt(3 - 3*value*value);
-
-            i = - 2*sqrtP*value - aBy3;
-            ii = sqrtP*(value + delta) - aBy3;
-            iii = sqrtP*(value - delta) - aBy3;
-        }
-
-        // One real root, two imaginary roots
-        // based on the above logic, PPP must be less than QQ
-        else
-        {
-            WarningInFunction
-                << "complex eigenvalues detected for tensor: " << t
-                << endl;
-
-            if (mag(P) < SMALL)
-            {
-                i = cbrt(QQ/2);
-            }
-            else
-            {
-                scalar w = cbrt(- Q - sqrt(QQ - PPP));
-                i = w + P/w - aBy3;
-            }
-
-            return vector(-VGREAT, i, VGREAT);
+            case roots::real:
+                lambda[i] = roots[i];
+                break;
+            case roots::complex:
+                WarningInFunction
+                    << "Complex eigenvalues detected for tensor: " << t
+                    << endl;
+                lambda[i] = 0;
+                break;
+            case roots::posInf:
+                lambda[i] = VGREAT;
+                break;
+            case roots::negInf:
+                lambda[i] = - VGREAT;
+                break;
+            case roots::nan:
+                FatalErrorInFunction
+                    << "Eigenvalue calculation failed for tensor: " << t
+                    << exit(FatalError);
         }
     }
 
     // Sort the eigenvalues into ascending order
-    if (i > ii)
+    if (lambda.x() > lambda.y())
     {
-        Swap(i, ii);
+        Swap(lambda.x(), lambda.y());
+    }
+    if (lambda.y() > lambda.z())
+    {
+        Swap(lambda.y(), lambda.z());
+    }
+    if (lambda.x() > lambda.y())
+    {
+        Swap(lambda.x(), lambda.y());
     }
 
-    if (ii > iii)
-    {
-        Swap(ii, iii);
-    }
-
-    if (i > ii)
-    {
-        Swap(i, ii);
-    }
-
-    return vector(i, ii, iii);
+    return lambda;
 }
 
 
 Foam::vector Foam::eigenVector
 (
-    const tensor& t,
-    const scalar lambda
+    const tensor& T,
+    const scalar lambda,
+    const vector& direction1,
+    const vector& direction2
 )
 {
-    // Constantly rotating direction ensures different eigenvectors are
-    // generated when called sequentially with a multiple eigenvalue
-    static vector direction(1,0,0);
-    vector oldDirection(direction);
-    scalar temp = direction[2];
-    direction[2] = direction[1];
-    direction[1] = direction[0];
-    direction[0] = temp;
-
     // Construct the linear system for this eigenvalue
-    tensor A(t - lambda*I);
+    tensor A(T - lambda*I);
 
     // Determinants of the 2x2 sub-matrices used to find the eigenvectors
     scalar sd0, sd1, sd2;
@@ -252,9 +192,9 @@ Foam::vector Foam::eigenVector
     }
 
     // Sub-determinants for a repeated eigenvalue
-    sd0 = A.yy()*direction.z() - A.yz()*direction.y();
-    sd1 = A.zz()*direction.x() - A.zx()*direction.z();
-    sd2 = A.xx()*direction.y() - A.xy()*direction.x();
+    sd0 = A.yy()*direction1.z() - A.yz()*direction1.y();
+    sd1 = A.zz()*direction1.x() - A.zx()*direction1.z();
+    sd2 = A.xx()*direction1.y() - A.xy()*direction1.x();
     magSd0 = mag(sd0);
     magSd1 = mag(sd1);
     magSd2 = mag(sd2);
@@ -265,8 +205,8 @@ Foam::vector Foam::eigenVector
         vector ev
         (
             1,
-            (A.yz()*direction.x() - direction.z()*A.yx())/sd0,
-            (direction.y()*A.yx() - A.yy()*direction.x())/sd0
+            (A.yz()*direction1.x() - direction1.z()*A.yx())/sd0,
+            (direction1.y()*A.yx() - A.yy()*direction1.x())/sd0
         );
 
         return ev/mag(ev);
@@ -275,9 +215,9 @@ Foam::vector Foam::eigenVector
     {
         vector ev
         (
-            (direction.z()*A.zy() - A.zz()*direction.y())/sd1,
+            (direction1.z()*A.zy() - A.zz()*direction1.y())/sd1,
             1,
-            (A.zx()*direction.y() - direction.x()*A.zy())/sd1
+            (A.zx()*direction1.y() - direction1.x()*A.zy())/sd1
         );
 
         return ev/mag(ev);
@@ -286,8 +226,8 @@ Foam::vector Foam::eigenVector
     {
         vector ev
         (
-            (A.xy()*direction.z() - direction.y()*A.xz())/sd2,
-            (direction.x()*A.xz() - A.xx()*direction.z())/sd2,
+            (A.xy()*direction1.z() - direction1.y()*A.xz())/sd2,
+            (direction1.x()*A.xz() - A.xx()*direction1.z())/sd2,
             1
         );
 
@@ -295,40 +235,57 @@ Foam::vector Foam::eigenVector
     }
 
     // Triple eigenvalue
-    return oldDirection;
+    return direction1^direction2;
 }
 
 
-Foam::tensor Foam::eigenVectors(const tensor& t)
+Foam::tensor Foam::eigenVectors(const tensor& T, const vector& lambdas)
 {
-    vector evals(eigenValues(t));
+    vector Ux(1, 0, 0), Uy(0, 1, 0), Uz(0, 0, 1);
 
-    tensor evs
-    (
-        eigenVector(t, evals.x()),
-        eigenVector(t, evals.y()),
-        eigenVector(t, evals.z())
-    );
+    Ux = eigenVector(T, lambdas.x(), Uy, Uz);
+    Uy = eigenVector(T, lambdas.y(), Uz, Ux);
+    Uz = eigenVector(T, lambdas.z(), Ux, Uy);
 
-    return evs;
+    return tensor(Ux, Uy, Uz);
 }
 
 
-Foam::vector Foam::eigenValues(const symmTensor& t)
+Foam::tensor Foam::eigenVectors(const tensor& T)
 {
-    return eigenValues(tensor(t));
+    const vector lambdas(eigenValues(T));
+
+    return eigenVectors(T, lambdas);
 }
 
 
-Foam::vector Foam::eigenVector(const symmTensor& t, const scalar lambda)
+Foam::vector Foam::eigenValues(const symmTensor& T)
 {
-    return eigenVector(tensor(t), lambda);
+    return eigenValues(tensor(T));
 }
 
 
-Foam::tensor Foam::eigenVectors(const symmTensor& t)
+Foam::vector Foam::eigenVector
+(
+    const symmTensor& T,
+    const scalar lambda,
+    const vector& direction1,
+    const vector& direction2
+)
 {
-    return eigenVectors(tensor(t));
+    return eigenVector(tensor(T), lambda, direction1, direction2);
+}
+
+
+Foam::tensor Foam::eigenVectors(const symmTensor& T, const vector& lambdas)
+{
+    return eigenVectors(tensor(T), lambdas);
+}
+
+
+Foam::tensor Foam::eigenVectors(const symmTensor& T)
+{
+    return eigenVectors(tensor(T));
 }
 
 

src/OpenFOAM/primitives/Tensor/tensor/tensor.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2017 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -50,13 +50,27 @@ namespace Foam
 
 typedef Tensor<scalar> tensor;
 
-vector eigenValues(const tensor&);
-vector eigenVector(const tensor&, const scalar lambda);
-tensor eigenVectors(const tensor&);
+vector eigenValues(const tensor& T);
+vector eigenVector
+(
+    const tensor& T,
+    const scalar lambda,
+    const vector& direction1,
+    const vector& direction2
+);
+tensor eigenVectors(const tensor& T, const vector& lambdas);
+tensor eigenVectors(const tensor& T);
 
-vector eigenValues(const symmTensor&);
-vector eigenVector(const symmTensor&, const scalar lambda);
-tensor eigenVectors(const symmTensor&);
+vector eigenValues(const symmTensor& T);
+vector eigenVector
+(
+    const symmTensor& T,
+    const scalar lambda,
+    const vector& direction1,
+    const vector& direction2
+);
+tensor eigenVectors(const symmTensor& T, const vector& lambdas);
+tensor eigenVectors(const symmTensor& T);
 
 //- Data associated with tensor type are contiguous
 template<>

src/OpenFOAM/primitives/Tensor2D/tensor2D/tensor2D.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2017 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -24,6 +24,7 @@ License
 \*---------------------------------------------------------------------------*/
 
 #include "tensor2D.H"
+#include "quadraticEqn.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -85,95 +86,96 @@ const Foam::tensor2D Foam::tensor2D::I
 
 Foam::vector2D Foam::eigenValues(const tensor2D& t)
 {
-    scalar i = 0;
-    scalar ii = 0;
+    // Coefficients of the characteristic quadratic polynomial (a = 1)
+    const scalar b = - t.xx() - t.yy();
+    const scalar c = t.xx()*t.yy() - t.xy()*t.yx();
 
-    if (mag(t.xy()) < SMALL && mag(t.yx()) < SMALL)
+    // Solve
+    Roots<2> roots = quadraticEqn(1, b, c).roots();
+
+    // Check the root types
+    vector2D lambda = vector2D::zero;
+    forAll(roots, i)
     {
-        i = t.xx();
-        ii = t.yy();
-    }
-    else
-    {
-        scalar mb = t.xx() + t.yy();
-        scalar c = t.xx()*t.yy() - t.xy()*t.yx();
-
-        // If there is a zero root
-        if (mag(c) < SMALL)
+        switch (roots.type(i))
         {
-            i = 0;
-            ii = mb;
-        }
-        else
-        {
-            scalar disc = sqr(mb) - 4*c;
-
-            if (disc > 0)
-            {
-                scalar q = sqrt(disc);
-
-                i = 0.5*(mb - q);
-                ii = 0.5*(mb + q);
-            }
-            else
-            {
+            case roots::real:
+                lambda[i] = roots[i];
+                break;
+            case roots::complex:
+                WarningInFunction
+                    << "Complex eigenvalues detected for tensor: " << t
+                    << endl;
+                lambda[i] = 0;
+                break;
+            case roots::posInf:
+                lambda[i] = VGREAT;
+                break;
+            case roots::negInf:
+                lambda[i] = - VGREAT;
+                break;
+            case roots::nan:
                 FatalErrorInFunction
-                    << "zero and complex eigenvalues in tensor2D: " << t
-                    << abort(FatalError);
-            }
+                    << "Eigenvalue calculation failed for tensor: " << t
+                    << exit(FatalError);
         }
     }
 
     // Sort the eigenvalues into ascending order
-    if (i > ii)
+    if (lambda.x() > lambda.y())
     {
-        Swap(i, ii);
+        Swap(lambda.x(), lambda.y());
     }
 
-    return vector2D(i, ii);
+    return lambda;
 }
 
 
-Foam::vector2D Foam::eigenVector(const tensor2D& t, const scalar lambda)
+Foam::vector2D Foam::eigenVector
+(
+    const tensor2D& T,
+    const scalar lambda,
+    const vector2D& direction1
+)
 {
-    if (lambda < SMALL)
+    // Construct the linear system for this eigenvalue
+    tensor2D A(T - lambda*tensor2D::I);
+
+    // Evaluate the eigenvector using the largest divisor
+    if (mag(A.yy()) > mag(A.xx()) && mag(A.yy()) > SMALL)
     {
-        return vector2D::zero;
+        vector2D ev(1, - A.yx()/A.yy());
+
+        return ev/mag(ev);
+    }
+    else if (mag(A.xx()) > SMALL)
+    {
+        vector2D ev(- A.xy()/A.xx(), 1);
+
+        return ev/mag(ev);
     }
 
-    if (mag(t.xy()) < SMALL && mag(t.yx()) < SMALL)
-    {
-        if (lambda > min(t.xx(), t.yy()))
-        {
-            return vector2D(1, 0);
-        }
-        else
-        {
-            return vector2D(0, 1);
-        }
-    }
-    else if (mag(t.xy()) < SMALL)
-    {
-        return vector2D(lambda - t.yy(), t.yx());
-    }
-    else
-    {
-        return vector2D(t.xy(), lambda - t.yy());
-    }
+    // Repeated eigenvalue
+    return vector2D(- direction1.y(), direction1.x());
 }
 
 
-Foam::tensor2D Foam::eigenVectors(const tensor2D& t)
+Foam::tensor2D Foam::eigenVectors(const tensor2D& T, const vector2D& lambdas)
 {
-    vector2D evals(eigenValues(t));
+    vector2D Ux(1, 0), Uy(0, 1);
 
-    tensor2D evs
-    (
-        eigenVector(t, evals.x()),
-        eigenVector(t, evals.y())
-    );
+    Ux = eigenVector(T, lambdas.x(), Uy);
+    Uy = eigenVector(T, lambdas.y(), Ux);
 
-    return evs;
+    return tensor2D(Ux, Uy);
+}
+
+
+Foam::tensor2D Foam::eigenVectors(const tensor2D& T)
+{
+    const vector2D lambdas(eigenValues(T));
+
+    return eigenVectors(T, lambdas);
 }
 
 

src/OpenFOAM/primitives/Tensor2D/tensor2D/tensor2D.H

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2017 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -49,7 +49,13 @@ namespace Foam
 typedef Tensor2D<scalar> tensor2D;
 
 vector2D eigenValues(const tensor2D& t);
-vector2D eigenVector(const tensor2D& t, const scalar lambda);
+vector2D eigenVector
+(
+    const tensor2D& t,
+    const scalar lambda,
+    const vector2D& direction1
+);
+tensor2D eigenVectors(const tensor2D& t, const vector2D& lambdas);
 tensor2D eigenVectors(const tensor2D& t);
 
 //- Data associated with tensor2D type are contiguous

src/OpenFOAM/primitives/polynomialEqns/Roots.H

@@ -0,0 +1,131 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::Roots
+
+Description
+    Templated storage for the roots of polynomial equations, plus flags to
+    indicate the nature of the roots.
+
+SourceFiles
+    RootsI.H
+    Roots.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Roots_H
+#define Roots_H
+
+#include "VectorSpace.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace roots
+{
+
+//- Types of root
+enum type
+{
+    real = 0,
+    complex,
+    posInf,
+    negInf,
+    nan
+};
+
+}
+
+/*---------------------------------------------------------------------------*\
+                         Class Roots Declaration
+\*---------------------------------------------------------------------------*/
+
+template<direction N>
+class Roots
+:
+    public VectorSpace<Roots<N>, scalar, N>
+{
+    // Private data
+
+        //- Root types, encoded into a single integer
+        label types_;
+
+public:
+
+    // Constructors
+
+        //- Construct null
+        inline Roots();
+
+        //- Construct with a uniform value
+        inline Roots(const roots::type t, const scalar x);
+
+        //- Construct by concatenation
+        inline Roots
+        (
+            const roots::type t,
+            const scalar x,
+            const Roots<N - 1>& xs
+        );
+
+        //- Construct by concatenation
+        inline Roots
+        (
+            const Roots<N - 1>& xs,
+            const roots::type t,
+            const scalar x
+        );
+
+        //- Construct by concatenation
+        template <direction M>
+        inline Roots(const Roots<M>& xs, const Roots<N - M>& ys);
+
+
+    // Member Functions
+
+        //- Set the type of the i-th root
+        inline void type(const direction i, const roots::type t);
+
+        //- Return the type of the i-th root
+        inline roots::type type(const direction i) const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "RootsI.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/OpenFOAM/primitives/polynomialEqns/RootsI.H

@@ -0,0 +1,136 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+template <Foam::direction N>
+inline Foam::Roots<N>::Roots()
+:
+    types_(0)
+{
+    forAll(*this, i)
+    {
+        type(i, roots::nan);
+    }
+}
+
+
+template <Foam::direction N>
+inline Foam::Roots<N>::Roots(const roots::type t, const scalar x)
+:
+    types_(0)
+{
+    forAll(*this, i)
+    {
+        this->v_[i] = x;
+        type(i, t);
+    }
+}
+
+
+template <Foam::direction N>
+inline Foam::Roots<N>::Roots
+(
+    const roots::type t,
+    const scalar x,
+    const Roots<N - 1>& xs
+)
+:
+    types_(0)
+{
+    this->v_[0] = x;
+    type(0, t);
+    forAll(xs, i)
+    {
+        this->v_[i+1] = xs[i];
+        type(i + 1, xs.type(i));
+    }
+}
+
+
+template <Foam::direction N>
+inline Foam::Roots<N>::Roots
+(
+    const Roots<N - 1>& xs,
+    const roots::type t,
+    const scalar x
+)
+:
+    types_(0)
+{
+    forAll(xs, i)
+    {
+        this->v_[i] = xs[i];
+        type(i, xs.type(i));
+    }
+    this->v_[N-1] = x;
+    type(N - 1, t);
+}
+
+
+template <Foam::direction N>
+template <Foam::direction M>
+inline Foam::Roots<N>::Roots
+(
+    const Roots<M>& xs,
+    const Roots<N - M>& ys
+)
+:
+    types_(0)
+{
+    forAll(xs, i)
+    {
+        this->v_[i] = xs[i];
+        type(i, xs.type(i));
+    }
+    forAll(ys, i)
+    {
+        this->v_[i + M] = ys[i];
+        type(i + M, ys.type(i));
+    }
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+template <Foam::direction N>
+inline void Foam::Roots<N>::type
+(
+    const direction i,
+    const roots::type t
+)
+{
+    types_ += (t - type(i)) << 3*i;
+}
+
+
+template <Foam::direction N>
+inline Foam::roots::type Foam::Roots<N>::type(const direction i) const
+{
+    return static_cast<roots::type>((types_ >> 3*i) & 7);
+}
+
+
+// ************************************************************************* //

src/OpenFOAM/primitives/polynomialEqns/cubicEqn/cubicEqn.C

@@ -0,0 +1,164 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "linearEqn.H"
+#include "quadraticEqn.H"
+#include "cubicEqn.H"
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+Foam::Roots<3> Foam::cubicEqn::roots() const
+{
+    /*
+
+    This function solves a cubic equation of the following form:
+
+        a*x^3 + b*x^2 + c*x + d = 0
+          x^3 + B*x^2 + C*x + D = 0
+
+    The following two substitutions are used:
+
+        x = t - B/3
+        t = w - P/3/w
+
+    This reduces the problem to a quadratic in w^3.
+
+        w^6 + Q*w^3 - P = 0
+
+    Where Q and P are given in the code below.
+
+    The properties of the cubic can be related to the properties of this
+    quadratic in w^3. If it has a repeated root a zero, the cubic has a tripl
+    root. If it has a repeated root not at zero, the cubic has two real roots,
+    one repeated and one not. If it has two complex roots, the cubic has three
+    real roots. If it has two real roots, then the cubic has one real root and
+    two complex roots.
+
+    This is solved for the most numerically accurate value of w^3. See the
+    quadratic function for details on how to pick a value. This single value of
+    w^3 can yield up to three cube roots for w, which relate to the three
+    solutions for x.
+
+    Only a single root, or pair of conjugate roots, is directly evaluated; the
+    one, or ones with the lowest relative numerical error. Root identities are
+    then used to recover the remaining roots, possibly utilising a quadratic
+    and/or linear solution. This seems to be a good way of maintaining the
+    accuracy of roots at very different magnitudes.
+
+    */
+
+    const scalar a = this->a();
+    const scalar b = this->b();
+    const scalar c = this->c();
+    const scalar d = this->d();
+
+    if (a == 0)
+    {
+        return Roots<3>(quadraticEqn(b, c, d).roots(), roots::nan, 0);
+    }
+
+    // This is assumed not to over- or under-flow. If it does, all bets are off.
+    const scalar p = c*a - b*b/3;
+    const scalar q = b*b*b*(2.0/27.0) - b*c*a/3 + d*a*a;
+    const scalar disc = p*p*p/27 + q*q/4;
+
+    // How many roots of what types are available?
+    const bool oneReal = disc == 0 && p == 0;
+    const bool twoReal = disc == 0 && p != 0;
+    const bool threeReal = disc < 0;
+    //const bool oneRealTwoComplex = disc > 0;
+
+    static const scalar sqrt3 = sqrt(3.0);
+
+    scalar x;
+
+    if (oneReal)
+    {
+        const Roots<1> r = linearEqn(- a, b/3).roots();
+        return Roots<3>(r.type(0), r[0]);
+    }
+    else if (twoReal)
+    {
+        if (q*b > 0)
+        {
+            x = - 2*cbrt(q/2) - b/3;
+        }
+        else
+        {
+            x = cbrt(q/2) - b/3;
+            const Roots<1> r = linearEqn(- a, x).roots();
+            return Roots<3>(Roots<2>(r, r), linearEqn(x*x, a*d).roots());
+        }
+    }
+    else if (threeReal)
+    {
+        const scalar wCbRe = - q/2, wCbIm = sqrt(- disc);
+        const scalar wAbs = cbrt(hypot(wCbRe, wCbIm));
+        const scalar wArg = atan2(wCbIm, wCbRe)/3;
+        const scalar wRe = wAbs*cos(wArg), wIm = wAbs*sin(wArg);
+        if (b > 0)
+        {
+            x = - wRe - mag(wIm)*sqrt3 - b/3;
+        }
+        else
+        {
+            x = 2*wRe - b/3;
+        }
+    }
+    else // if (oneRealTwoComplex)
+    {
+        const scalar wCb = - q/2 - sign(q)*sqrt(disc);
+        const scalar w = cbrt(wCb);
+        const scalar t = w - p/(3*w);
+        if (p + t*b < 0)
+        {
+            x = t - b/3;
+        }
+        else
+        {
+            const scalar xRe = - t/2 - b/3, xIm = sqrt3/2*(w + p/3/w);
+            x = - a*a*d/(xRe*xRe + xIm*xIm);
+
+            // This form of solving for the remaining roots seems more stable
+            // for this case. This has been determined by trial and error.
+            return
+                Roots<3>
+                (
+                    linearEqn(- a, x).roots(),
+                    quadraticEqn(a*x, x*x + b*x, - a*d).roots()
+                );
+        }
+    }
+
+    return
+        Roots<3>
+        (
+            linearEqn(- a, x).roots(),
+            quadraticEqn(- x*x, c*x + a*d, d*x).roots()
+        );
+}
+
+
+// ************************************************************************* //

src/OpenFOAM/primitives/polynomialEqns/cubicEqn/cubicEqn.H

@@ -0,0 +1,115 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::cubicEqn
+
+Description
+    Cubic equation of the form a*x^3 + b*x^2 + c*x + d = 0
+
+SourceFiles
+    cubicEqnI.H
+    cubicEqn.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef cubicEqn_H
+#define cubicEqn_H
+
+#include "Roots.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                         Class cubicEqn Declaration
+\*---------------------------------------------------------------------------*/
+
+class cubicEqn
+:
+    public VectorSpace<cubicEqn, scalar, 4>
+{
+public:
+
+    //- Component labeling enumeration
+    enum components { A, B, C, D };
+
+
+    // Constructors
+
+        //- Construct null
+        inline cubicEqn();
+
+        //- Construct initialized to zero
+        inline cubicEqn(const Foam::zero);
+
+        //- Construct from components
+        inline cubicEqn
+        (
+            const scalar a,
+            const scalar b,
+            const scalar c,
+            const scalar d
+        );
+
+
+    // Member Functions
+
+        // Access
+
+            inline scalar a() const;
+            inline scalar b() const;
+            inline scalar c() const;
+            inline scalar d() const;
+
+            inline scalar& a();
+            inline scalar& b();
+            inline scalar& c();
+            inline scalar& d();
+
+        //- Evaluate at x
+        inline scalar value(const scalar x) const;
+
+        //- Estimate the error of evaluation at x
+        inline scalar error(const scalar x) const;
+
+        //- Get the roots
+        Roots<3> roots() const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "cubicEqnI.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/OpenFOAM/primitives/polynomialEqns/cubicEqn/cubicEqnI.H

@@ -0,0 +1,115 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+inline Foam::cubicEqn::cubicEqn()
+{}
+
+
+inline Foam::cubicEqn::cubicEqn(const Foam::zero)
+:
+    VectorSpace<cubicEqn, scalar, 4>(Foam::zero())
+{}
+
+
+inline Foam::cubicEqn::cubicEqn
+(
+    const scalar a,
+    const scalar b,
+    const scalar c,
+    const scalar d
+)
+{
+    this->v_[A] = a;
+    this->v_[B] = b;
+    this->v_[C] = c;
+    this->v_[D] = d;
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+inline Foam::scalar Foam::cubicEqn::a() const
+{
+    return this->v_[A];
+}
+
+
+inline Foam::scalar Foam::cubicEqn::b() const
+{
+    return this->v_[B];
+}
+
+
+inline Foam::scalar Foam::cubicEqn::c() const
+{
+    return this->v_[C];
+}
+
+
+inline Foam::scalar Foam::cubicEqn::d() const
+{
+    return this->v_[D];
+}
+
+
+inline Foam::scalar& Foam::cubicEqn::a()
+{
+    return this->v_[A];
+}
+
+
+inline Foam::scalar& Foam::cubicEqn::b()
+{
+    return this->v_[B];
+}
+
+
+inline Foam::scalar& Foam::cubicEqn::c()
+{
+    return this->v_[C];
+}
+
+
+inline Foam::scalar& Foam::cubicEqn::d()
+{
+    return this->v_[D];
+}
+
+
+inline Foam::scalar Foam::cubicEqn::value(const scalar x) const
+{
+    return x*(x*(x*a() + b()) + c()) + d();
+}
+
+
+inline Foam::scalar Foam::cubicEqn::error(const scalar x) const
+{
+    return mag(SMALL*x*(x*(x*3*a() + 2*b()) + c()));
+}
+
+
+// ************************************************************************* //

src/OpenFOAM/primitives/polynomialEqns/linearEqn/linearEqn.H

@@ -0,0 +1,104 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::linearEqn
+
+Description
+    Linear equation of the form a*x + b = 0
+
+SourceFiles
+    linearEqnI.H
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef linearEqn_H
+#define linearEqn_H
+
+#include "Roots.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                         Class linearEqn Declaration
+\*---------------------------------------------------------------------------*/
+
+class linearEqn
+:
+    public VectorSpace<linearEqn, scalar, 2>
+{
+public:
+
+    //- Component labeling enumeration
+    enum components { A, B };
+
+
+    // Constructors
+
+        //- Construct null
+        inline linearEqn();
+
+        //- Construct initialized to zero
+        inline linearEqn(const Foam::zero);
+
+        //- Construct from components
+        inline linearEqn(const scalar a, const scalar b);
+
+
+    // Member Functions
+
+        // Access
+
+            inline scalar a() const;
+            inline scalar b() const;
+
+            inline scalar& a();
+            inline scalar& b();
+
+        //- Evaluate at x
+        inline scalar value(const scalar x) const;
+
+        //- Estimate the error of evaluation at x
+        inline scalar error(const scalar x) const;
+
+        //- Get the roots
+        inline Roots<1> roots() const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "linearEqnI.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/OpenFOAM/primitives/polynomialEqns/linearEqn/linearEqnI.H

@@ -0,0 +1,111 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+inline Foam::linearEqn::linearEqn()
+{}
+
+
+inline Foam::linearEqn::linearEqn(const Foam::zero)
+:
+    VectorSpace<linearEqn, scalar, 2>(Foam::zero())
+{}
+
+
+inline Foam::linearEqn::linearEqn(const scalar a, const scalar b)
+{
+    this->v_[A] = a;
+    this->v_[B] = b;
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+inline Foam::scalar Foam::linearEqn::a() const
+{
+    return this->v_[A];
+}
+
+
+inline Foam::scalar Foam::linearEqn::b() const
+{
+    return this->v_[B];
+}
+
+
+inline Foam::scalar& Foam::linearEqn::a()
+{
+    return this->v_[A];
+}
+
+
+inline Foam::scalar& Foam::linearEqn::b()
+{
+    return this->v_[B];
+}
+
+
+inline Foam::scalar Foam::linearEqn::value(const scalar x) const
+{
+    return x*a() + b();
+}
+
+
+inline Foam::scalar Foam::linearEqn::error(const scalar x) const
+{
+    return mag(SMALL*x*a());
+}
+
+
+inline Foam::Roots<1> Foam::linearEqn::roots() const
+{
+    /*
+
+    This function solves a linear equation of the following form:
+
+        a*x + b = 0
+          x + B = 0
+
+    */
+
+    const scalar a = this->a();
+    const scalar b = this->b();
+
+    if (a == 0)
+    {
+        return Roots<1>(roots::nan, 0);
+    }
+
+    if (mag(b/VGREAT) >= mag(a))
+    {
+        return Roots<1>(sign(a) == sign(b) ? roots::negInf : roots::posInf, 0);
+    }
+
+    return Roots<1>(roots::real, - b/a);
+}
+
+
+// ************************************************************************* //

src/OpenFOAM/primitives/polynomialEqns/quadraticEqn/quadraticEqn.C

@@ -0,0 +1,88 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "linearEqn.H"
+#include "quadraticEqn.H"
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+Foam::Roots<2> Foam::quadraticEqn::roots() const
+{
+    /*
+
+    This function solves a quadraticEqn equation of the following form:
+
+        a*x^2 + b*x + c = 0
+          x^2 + B*x + C = 0
+
+    The quadraticEqn formula is as follows:
+
+        x = - B/2 +- sqrt(B*B - 4*C)/2
+
+    If the sqrt generates a complex number, this provides the result. If not
+    then the real root with the smallest floating point error is calculated.
+
+        x0 = - B/2 - sign(B)*sqrt(B*B - 4*C)/2
+
+    The other root is the obtained using an identity.
+
+        x1 = C/x0
+
+    */
+
+    const scalar a = this->a();
+    const scalar b = this->b();
+    const scalar c = this->c();
+
+    if (a == 0)
+    {
+        return Roots<2>(linearEqn(b, c).roots(), roots::nan, 0);
+    }
+
+    // This is assumed not to over- or under-flow. If it does, all bets are off.
+    const scalar disc = b*b/4 - a*c;
+
+    // How many roots of what types are available?
+    const bool oneReal = disc == 0;
+    const bool twoReal = disc > 0;
+    //const bool twoComplex = disc < 0;
+
+    if (oneReal)
+    {
+        const Roots<1> r = linearEqn(- a, b/2).roots();
+        return Roots<2>(r, r);
+    }
+    else if (twoReal)
+    {
+        const scalar x = - b/2 - sign(b)*sqrt(disc);
+        return Roots<2>(linearEqn(- a, x).roots(), linearEqn(- x, c).roots());
+    }
+    else // if (twoComplex)
+    {
+        return Roots<2>(roots::complex, 0);
+    }
+}
+
+// ************************************************************************* //

src/OpenFOAM/primitives/polynomialEqns/quadraticEqn/quadraticEqn.H

@@ -0,0 +1,107 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::quadraticEqn
+
+Description
+    Quadratic equation of the form a*x^2 + b*x + c = 0
+
+SourceFiles
+    quadraticEqnI.H
+    quadraticEqn.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef quadraticEqn_H
+#define quadraticEqn_H
+
+#include "Roots.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                         Class quadraticEqn Declaration
+\*---------------------------------------------------------------------------*/
+
+class quadraticEqn
+:
+    public VectorSpace<quadraticEqn, scalar, 3>
+{
+public:
+
+    //- Component labeling enumeration
+    enum components { A, B, C };
+
+
+    // Constructors
+
+        //- Construct null
+        inline quadraticEqn();
+
+        //- Construct initialized to zero
+        inline quadraticEqn(const Foam::zero);
+
+        //- Construct from components
+        inline quadraticEqn(const scalar a, const scalar b, const scalar c);
+
+
+    // Member Functions
+
+        // Access
+
+            inline scalar a() const;
+            inline scalar b() const;
+            inline scalar c() const;
+
+            inline scalar& a();
+            inline scalar& b();
+            inline scalar& c();
+
+        //- Evaluate at x
+        inline scalar value(const scalar x) const;
+
+        //- Estimate the error of evaluation at x
+        inline scalar error(const scalar x) const;
+
+        //- Get the roots
+        Roots<2> roots() const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "quadraticEqnI.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/OpenFOAM/primitives/polynomialEqns/quadraticEqn/quadraticEqnI.H

@@ -0,0 +1,101 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2017 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+inline Foam::quadraticEqn::quadraticEqn()
+{}
+
+
+inline Foam::quadraticEqn::quadraticEqn(const Foam::zero)
+:
+    VectorSpace<quadraticEqn, scalar, 3>(Foam::zero())
+{}
+
+
+inline Foam::quadraticEqn::quadraticEqn
+(
+    const scalar a,
+    const scalar b,
+    const scalar c
+)
+{
+    this->v_[A] = a;
+    this->v_[B] = b;
+    this->v_[C] = c;
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+inline Foam::scalar Foam::quadraticEqn::a() const
+{
+    return this->v_[A];
+}
+
+
+inline Foam::scalar Foam::quadraticEqn::b() const
+{
+    return this->v_[B];
+}
+
+
+inline Foam::scalar Foam::quadraticEqn::c() const
+{
+    return this->v_[C];
+}
+
+
+inline Foam::scalar& Foam::quadraticEqn::a()
+{
+    return this->v_[A];
+}
+
+
+inline Foam::scalar& Foam::quadraticEqn::b()
+{
+    return this->v_[B];
+}
+
+
+inline Foam::scalar& Foam::quadraticEqn::c()
+{
+    return this->v_[C];
+}
+
+
+inline Foam::scalar Foam::quadraticEqn::value(const scalar x) const
+{
+    return x*(x*a() + b()) + c();
+}
+
+
+inline Foam::scalar Foam::quadraticEqn::error(const scalar x) const
+{
+    return mag(SMALL*x*(x*2*a() + b()));
+}
+
+
+// ************************************************************************* //

src/dynamicMesh/polyTopoChange/polyTopoChange/edgeCollapser.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011-2016 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2017 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -458,7 +458,7 @@ void Foam::edgeCollapser::faceCollapseAxisAndAspectRatio
             // normal, as it has the greatest value.  The minimum eigenvalue
             // is the dominant collapse axis for high aspect ratio faces.
 
-            collapseAxis = eigenVector(J, eVals.x());
+            collapseAxis = eigenVectors(J, eVals).x();
 
             // The inertia calculation describes the mass distribution as a
             // function of distance squared to the axis, so the square root of