[niko992]

I have to use the formula

gradient(f-velocity_X)

where f-velocity_X is a number
but when i use this there appears the error message

ERROR: In C:\bbd\df0abce0\source-paraview\VTK\Common\Misc\vtkFunctionParser.cxx, line 1244
vtkFunctionParser (000001C154368D50): Syntax error: expecting a variable name;  see position 0


Warning: In C:\bbd\df0abce0\source-paraview\VTK\Filters\Core\vtkArrayCalculator.cxx, line 405
vtkPVArrayCalculator (000001C154448380): An error occurred when parsing the calculator's function.  See previous errors.

Someone can tells me what i do wrong?