pdegrad, Matlab, more output data than input

Hello,

I have a problem with the command pdegrad.

[ux,uy] = pdegrad(points,tri,dat);

dat and the mesh parameters comme form an other code that I download on Matlab.

Assume that the variable dat has N elements, points has N number of elements and tri has "t number of elements. Then, after computation of pdegrad the number of element of ux and uy will be t, because the gradient of u is evaluated at the center of each triangle. That's my problem, why it doesn't conserve the same length than dat, in other words compute the grad on each nodes. Because after, I need the product between ux and dat.

Thank you a lot for your help.

B.Y

Ps: You should know that computation of pdegrad gives the expected result

Answer 1

[Alan Weiss]

To get the values at the node points use pdeprtni.

Alan Weiss

MATLAB mathematical toolbox documentation