ENH: septernion: added slerp

src/OpenFOAM/primitives/septernion/septernion.C

@@ -59,6 +59,17 @@ Foam::word Foam::name(const septernion& s)
 }
 
 
+Foam::septernion Foam::slerp
+(
+    const septernion& qa,
+    const septernion& qb,
+    const scalar t
+)
+{
+    return septernion((1.0-t)*qa.t()+t*qb.t(), slerp(qa.r(), qb.r(), t));
+}
+
+
 // * * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * //
 
 Foam::Istream& Foam::operator>>(Istream& is, septernion& s)

src/OpenFOAM/primitives/septernion/septernion.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) 2011-2013 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -157,6 +157,13 @@ inline septernion inv(const septernion& tr);
 //- Return a string representation of a septernion
 word name(const septernion&);
 
+//- Spherical linear interpolation of septernions. 0 for qa, 1 for qb
+septernion slerp
+(
+    const septernion& qa,
+    const septernion& qb,
+    const scalar t
+);
 
 //- Data associated with septernion type are contiguous
 template<>