Add XScaling parameter to TabulatedFunction

Refs #11752

Code/Mantid/Framework/CurveFitting/inc/MantidCurveFitting/TabulatedFunction.h

@@ -102,7 +102,7 @@ class DLLExport TabulatedFunction : public API::ParamFunction,
   void clear() const;
 
   /// Evaluate the function for a list of arguments and given scaling factor
-  void eval(double scaling, double shift, double *out, const double *xValues,
+  void eval(double scaling, double shift, double xscale, double *out, const double *xValues,
             const size_t nData) const;
 
   /// Fill in the x and y value containers (m_xData and m_yData)

Code/Mantid/Framework/CurveFitting/src/TabulatedFunction.cpp

@@ -30,13 +30,14 @@ const int TabulatedFunction::defaultIndexValue = 0;
 TabulatedFunction::TabulatedFunction() : m_setupFinished(false) {
   declareParameter("Scaling", 1.0, "A scaling factor");
   declareParameter("Shift", 0.0, "Shift in the abscissa");
+  declareParameter("XScaling", 1.0, "Scaling factor in X");
   declareAttribute("FileName", Attribute("", true));
   declareAttribute("Workspace", Attribute(""));
   declareAttribute("WorkspaceIndex", Attribute(defaultIndexValue));
 }
 
 /// Evaluate the function for a list of arguments and given scaling factor
-void TabulatedFunction::eval(double scaling, double xshift, double *out,
+void TabulatedFunction::eval(double scaling, double xshift, double xscale, double *out,
                              const double *xValues, const size_t nData) const {
   if (nData == 0)
     return;
@@ -46,10 +47,11 @@ void TabulatedFunction::eval(double scaling, double xshift, double *out,
   if (size() == 0)
     return;
 
-  // shift the domain over which the function is defined
+  // shift and scale the domain over which the function is defined
   std::vector<double> xData(m_xData);
   for (std::vector<double>::iterator it = xData.begin(); it != xData.end();
        ++it) {
+    *it *= xscale;
     *it += xshift;
   }
 
@@ -100,7 +102,8 @@ void TabulatedFunction::function1D(double *out, const double *xValues,
                                    const size_t nData) const {
   const double scaling = getParameter("Scaling");
   const double xshift = getParameter("Shift");
-  eval(scaling, xshift, out, xValues, nData);
+  const double xscale = getParameter("XScaling");
+  eval(scaling, xshift, xscale, out, xValues, nData);
 }
 
 /**
@@ -115,24 +118,32 @@ void TabulatedFunction::functionDeriv1D(API::Jacobian *out,
                                         const size_t nData) {
   const double scaling = getParameter("Scaling");
   const double xshift = getParameter("Shift");
+  const double xscale = getParameter("XScaling");
   std::vector<double> tmp(nData);
   // derivative with respect to Scaling parameter
-  eval(1.0, xshift, tmp.data(), xValues, nData);
+  eval(1.0, xshift, xscale, tmp.data(), xValues, nData);
   for (size_t i = 0; i < nData; ++i) {
     out->set(i, 0, tmp[i]);
   }
 
-  // There is no unique definition for the partial derivative with respect
-  // to the Shift parameter. Here we take the central difference,
   const double dx =
       (xValues[nData - 1] - xValues[0]) / static_cast<double>(nData);
   std::vector<double> tmpplus(nData);
-  eval(scaling, xshift + dx, tmpplus.data(), xValues, nData);
   std::vector<double> tmpminus(nData);
-  eval(scaling, xshift - dx, tmpminus.data(), xValues, nData);
+
+  // There is no unique definition for the partial derivative with respect
+  // to the Shift parameter. Here we take the central difference,
+  eval(scaling, xshift + dx, xscale, tmpplus.data(), xValues, nData);
+  eval(scaling, xshift - dx, xscale, tmpminus.data(), xValues, nData);
   for (size_t i = 0; i < nData; ++i) {
     out->set(i, 1, (tmpplus[i] - tmpminus[i]) / (2 * dx));
   }
+
+  eval(scaling, xshift, xscale + dx, tmpplus.data(), xValues, nData);
+  eval(scaling, xshift, xscale - dx, tmpminus.data(), xValues, nData);
+  for (size_t i = 0; i < nData; ++i) {
+    out->set(i, 2, (tmpplus[i] - tmpminus[i]) / (2 * dx));
+  }
 }
 
 /// Clear all data

Code/Mantid/Framework/CurveFitting/test/TabulatedFunctionTest.h

@@ -50,19 +50,19 @@ class TabulatedFunctionTest : public CxxTest::TestSuite
     UserFunction fun;
     fun.setAttributeValue("Formula","exp(-x*x)");
     fun.function( x, y );
-    
+
     std::ofstream fil(m_asciiFileName.c_str());
     for(size_t i = 0; i < x.size(); ++i)
     {
       fil << x[i] << ' ' << y[i] << std::endl;
     }
 
   }
-  
+
   ~TabulatedFunctionTest()
   {
     Poco::File hAscii(m_asciiFileName);
-    if( hAscii.exists() ) 
+    if( hAscii.exists() )
     {
       hAscii.remove();
     }
@@ -205,12 +205,14 @@ class TabulatedFunctionTest : public CxxTest::TestSuite
     TS_ASSERT_EQUALS( fun.getParameter( "Scaling" ), 3.3 );
     fun.setParameter( "Shift", 0.0 );
     TS_ASSERT_EQUALS( fun.getParameter( "Shift" ), 0.0 );
+    fun.setParameter( "XScaling", 1.0 );
+    TS_ASSERT_EQUALS( fun.getParameter( "XScaling" ), 1.0 );
     FunctionDomain1DVector x(-5.0, 5.0, 83);
 
     FunctionValues y( x );
     fun.function( x, y );
 
-    Mantid::CurveFitting::Jacobian jac(x.size(),2);
+    Mantid::CurveFitting::Jacobian jac(x.size(),3);
     fun.functionDeriv(x, jac);
 
     for(size_t i = 0; i < x.size(); ++i)
@@ -239,28 +241,30 @@ class TabulatedFunctionTest : public CxxTest::TestSuite
 
   void test_factory_create_from_file()
   {
-      std::string inif = "name=TabulatedFunction,FileName=\"" + m_nexusFileName + "\",WorkspaceIndex=17,Scaling=2,Shift=0.02";
+      std::string inif = "name=TabulatedFunction,FileName=\"" + m_nexusFileName + "\",WorkspaceIndex=17,Scaling=2,Shift=0.02,XScaling=0.2";
       auto funf = Mantid::API::FunctionFactory::Instance().createInitialized(inif);
       TS_ASSERT( funf );
       TS_ASSERT_EQUALS( funf->getAttribute("Workspace").asString(), "");
       TS_ASSERT_EQUALS( funf->getAttribute("WorkspaceIndex").asInt(), 17);
       TS_ASSERT_EQUALS( funf->getAttribute("FileName").asUnquotedString(), m_nexusFileName);
       TS_ASSERT_EQUALS( funf->getParameter("Scaling"), 2.0);
       TS_ASSERT_EQUALS( funf->getParameter("Shift"), 0.02);
+      TS_ASSERT_EQUALS( funf->getParameter("XScaling"), 0.2);
   }
 
   void test_factory_create_from_workspace()
   {
       auto ws = WorkspaceCreationHelper::Create2DWorkspaceFromFunction(Fun(),1,-5.0,5.0,0.1,false);
       AnalysisDataService::Instance().add( "TABULATEDFUNCTIONTEST_WS", ws );
-      std::string inif = "name=TabulatedFunction,Workspace=TABULATEDFUNCTIONTEST_WS,WorkspaceIndex=71,Scaling=3.14,Shift=0.02";
+      std::string inif = "name=TabulatedFunction,Workspace=TABULATEDFUNCTIONTEST_WS,WorkspaceIndex=71,Scaling=3.14,Shift=0.02,XScaling=0.2";
       auto funf = Mantid::API::FunctionFactory::Instance().createInitialized(inif);
       TS_ASSERT( funf );
       TS_ASSERT_EQUALS( funf->getAttribute("Workspace").asString(), "TABULATEDFUNCTIONTEST_WS");
       TS_ASSERT_EQUALS( funf->getAttribute("WorkspaceIndex").asInt(), 71);
       TS_ASSERT_EQUALS( funf->getAttribute("FileName").asUnquotedString(), "");
       TS_ASSERT_EQUALS( funf->getParameter("Scaling"), 3.14);
       TS_ASSERT_EQUALS( funf->getParameter("Shift"), 0.02);
+      TS_ASSERT_EQUALS( funf->getParameter("XScaling"), 0.2);
       AnalysisDataService::Instance().clear();
   }