tangent plan at fixed point

hi , i works on face recognition and i need to plot a tangent plan to a face at a fixed point, so could anyone help me to find the tangent plan to 3d face at a point p(x0,y0,z0) with matlab ??

Answer 1

[Matt J]

You can use gradient() to calculate the normal to the plane.

[ramik]

how to use gradient() without knowing the analytic function of the 3d face ??

[Matt J]

From the documentation:

[FX,FY,FZ,...,FN] = gradient(F) returns the N components of the numerical gradient of F, where F is an array with N dimensions.