c# - How to emulate Vector3.TransformNormal -

i trying emulate vector3.transformnormal without directx library.

is able explain how function works, allow me recreate function?

so far know inputs , have seen description of does, don't know calculations.

public static vector3 transformnormal(     vector3 source,     matrix sourcematrix ) 

this should (didn't test)

public vector3 transformnormal(vector3 normal, matrix matrix) {         return new vector3     {         x = normal.x * matrix.m11 + normal.y * matrix.m21 + normal.z * matrix.m31,         y = normal.x * matrix.m12 + normal.y * matrix.m22 + normal.z * matrix.m32,         z = normal.x * matrix.m13 + normal.y * matrix.m23 + normal.z * matrix.m33     }; }