I have a function w with a coefficient A, I do some integrals with this function and then evaluate the derivative of the function respect to A equal to zero to solve for A. I want to assign this value to A, so this is what I am doing:
w = A Sin[ Pi x/L]
I = Integral[w^2,0,L]
This integrates and gives me a function of A^2, then I do:
Gives me a solution, with no problem, so I assign this value to A with
Also no errors, but if I type w again, A has not been replaced.
What am I missing?