functionObjects::log: Added optional switch to disable dimension checking:

Description
    Calculates the natural logarithm of the specified scalar field.

    Performs \f$ln(max(x, a))\f$ where \f$x\f$ is the field and \f$a\f$ an
    optional clip to handle 0 or negative \f$x\f$.  Dimension checking can
    optionally be suspended for this operation if \f$x\f$ is dimensioned.

    Example of function object specification:
    \verbatim
    log1
    {
        type            log;
        libs            ("libfieldFunctionObjects.so");
        field           p;
        clip            1e-3;
        checkDimensions no;
    }
    \endverbatim

    or using \c postProcess
    \verbatim
    postProcess -func 'log(p, clip=1e-3, checkDimensions=no)'
    \endverbatim

Usage
    \table
        Property        | Description               | Required | Default value
        type            | Type name: log            | yes      |
        clip            | Clip value                | no       |
        checkDimensions | Dimension checking switch | no       |
    \endtable

src/functionObjects/field/log/log.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     | Website:  https://openfoam.org
-    \\  /    A nd           | Copyright (C) 2018 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2018-2019 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -53,11 +53,28 @@ bool Foam::functionObjects::log::calc()
     {
         const volScalarField& x = lookupObject<volScalarField>(fieldName_);
 
-        return store
+        // Cache the current debug setting for dimensionSet
+        const bool dimensionSetDebug = dimensionSet::debug;
+
+        // Switch-off dimension checking if requested
+        if (!checkDimensions_)
+        {
+            dimensionSet::debug = 0;
+        }
+
+        bool stored = store
         (
             resultName_,
-            Foam::log(max(x, clip_))
+            clip_ ? Foam::log(max(x, clipValue_)) : Foam::log(x)
         );
+
+        // Reinstate dimension checking
+        if (!checkDimensions_)
+        {
+            dimensionSet::debug = dimensionSetDebug;
+        }
+
+        return stored;
     }
     else
     {
@@ -77,7 +94,10 @@ Foam::functionObjects::log::log
     const dictionary& dict
 )
 :
-    fieldExpression(name, runTime, dict)
+    fieldExpression(name, runTime, dict),
+    clip_(false),
+    clipValue_(0),
+    checkDimensions_(true)
 {
     read(dict);
 }
@@ -100,7 +120,13 @@ bool Foam::functionObjects::log::read(const dictionary& dict)
         resultName_ = "log(" + fieldName_ + ")";
     }
 
-    clip_ = dict.lookupOrDefault<scalar>("clip", 0);
+    if (dict.found("clip"))
+    {
+        clip_ = true;
+        dict.lookup("clip") >> clipValue_;
+    }
+
+    checkDimensions_ = dict.lookupOrDefault<Switch>("checkDimensions", true);
 
     return true;
 }

src/functionObjects/field/log/log.H

@@ -28,7 +28,33 @@ Description
     Calculates the natural logarithm of the specified scalar field.
 
     Performs \f$ln(max(x, a))\f$ where \f$x\f$ is the field and \f$a\f$ an
-    optional clip to handle 0 or negative \f$x\f$.
+    optional clip to handle 0 or negative \f$x\f$.  Dimension checking can
+    optionally be suspended for this operation if \f$x\f$ is dimensioned.
+
+    Example of function object specification:
+    \verbatim
+    log1
+    {
+        type            log;
+        libs            ("libfieldFunctionObjects.so");
+        field           p;
+        clip            1e-3;
+        checkDimensions no;
+    }
+    \endverbatim
+
+    or using \c postProcess
+    \verbatim
+    postProcess -func 'log(p, clip=1e-3, checkDimensions=no)'
+    \endverbatim
+
+Usage
+    \table
+        Property        | Description               | Required | Default value
+        type            | Type name: log            | yes      |
+        clip            | Clip value                | no       |
+        checkDimensions | Dimension checking switch | no       |
+    \endtable
 
 See also
     Foam::functionObjects::fieldExpression
@@ -61,8 +87,14 @@ class log
 {
     // Private Data
 
-        //- Optional clip (default is 0)
+        //- Optional clip, default = false
-        scalar clip_;
+        bool clip_;
+
+        //- Optional clip value
+        scalar clipValue_;
+
+        //- Optional dimension checking override
+        Switch checkDimensions_;
 
 
     // Private Member Functions