# Mesh an implicit function (python lambda)
**URL:** https://discourse.vtk.org/t/mesh-an-implicit-function-python-lambda/3838
**Category:** Support
**Created:** [July 23, 2020, 11:42am UTC](https://discourse.vtk.org/t/mesh-an-implicit-function-python-lambda/3838 "2020-07-23T11:42:35Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@T4mmi](https://discourse.vtk.org/u/T4mmi)
#### Post date: [July 23, 2020, 11:42am UTC](https://discourse.vtk.org/t/mesh-an-implicit-function-python-lambda/3838/1 "2020-07-23T11:42:35Z")
Hi all,
I’m looking for a VTK way to mesh any custom implicit function (as a python lambda with a signature of type `List[float[3]] -> float`)
From what I read `vtkSampleFunction` \> `vtkMarchingCubes` seems the way to go but I could not manage to derivate `vtkImplicitFunction` through the Python interface, nor find any example (even C++ meshing a `float(*)(double x[3])`)
😕
```auto
from vtk import vtkImplicitFunction
class vtkImplicitFunctor(vtkImplicitFunction):
def __init__ (self, functor: "List[float[3]] -> float", gradient: "List[float[3]] -> List[float[3]]"):
self.FunctionValue = functor
self.FunctionGradient = gradient
def EvaluateFunction(self, point: "List[float[3]]") -> float:
return self.FunctionValue(point)
def EvaluateGradient(self,point: "List[float[3]]") -> "List[float[3]]":
return self.FunctionGradient(point)
vtkImplicitFunctor(functor=lambda x,y,z: z, gradient=lambda x,y,z: [0,0,1])
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
in
----> 1 vtkImplicitFunctor(functor=lambda x,y,z: z, gradient=lambda x,y,z: [0,0,1])
TypeError: this is an abstract class and cannot be instantiated
```
---
### Author:  [@Cos0](https://discourse.vtk.org/u/Cos0)
#### Post date: [April 12, 2024, 6:07am UTC](https://discourse.vtk.org/t/mesh-an-implicit-function-python-lambda/3838/2 "2024-04-12T06:07:29Z")
Same question again, man, it’s really tough.