Fixed bug in evaluating tabulated functions

platforms/cuda/src/kernels/kEvaluateExpression.h

@@ -114,7 +114,7 @@ __device__ float kEvaluateExpression_kernel(Expression<SIZE>* expression, float*
                         if (op == CUSTOM)
                             STACK(stackPointer) = a*coeff.x+b*coeff.y+((a*a*a-a)*coeff.z+(b*b*b-b)*coeff.w)/(params.z*params.z);
                         else
-                            STACK(stackPointer) = (coeff.y-coeff.x)*params.z-((3.0f*a*a-1.0f)*coeff.z+(4.0f*b*b-1.0f)*coeff.w)/params.z;
+                            STACK(stackPointer) = (coeff.y-coeff.x)*params.z+((1.0f-3.0f*a*a)*coeff.z+(3.0f*b*b-1.0f)*coeff.w)/params.z;
                     }
                 }
             }

platforms/opencl/src/OpenCLExpressionUtilities.cpp

@@ -130,7 +130,7 @@ void OpenCLExpressionUtilities::processExpression(stringstream& out, const Expre
             if (valueNode != NULL)
                 out << valueName << " = a*coeff.x+b*coeff.y+((a*a*a-a)*coeff.z+(b*b*b-b)*coeff.w)/(params.z*params.z);\n";
             if (derivNode != NULL)
-                out << derivName << " = (coeff.y-coeff.x)*params.z-((3.0f*a*a-1.0f)*coeff.z+(4.0f*b*b-1.0f)*coeff.w)/params.z;\n";
+                out << derivName << " = (coeff.y-coeff.x)*params.z+((1.0f-3.0f*a*a)*coeff.z+(3.0f*b*b-1.0f)*coeff.w)/params.z;\n";
             out << "}\n";
             out << "}";
             break;