Here, i am sharing my codes. Please help if anyone know. Moreover, I want to do simulation on this codes. How to do simulation on this code so that i can see my solution how simulate at different time??.

poisson.edp (1.7 KB)

I sorry , but I do not understand what you want . You have no time in your equation so different time is no clean.

But please tell how i ger different L2-error so that i can compute order of convergence. I am getting same L2-error in every mesh size. Solution is uknown i want to compute L2-error and order of convergence. Please tell that i part. Thanks

real ccc= 2./(2*pi^2);
func uexact = ccc*sin(pi

*x)*

func Lapuexact= - ccc2

*sin(pi*y);func Lapuexact= - ccc

*pi^2*sin(pi*x)

*sin(pi*y);

Sir, why you using this, i don’t know eaxct solution then i want compute L2-error and order of convergence. That is, **i want to compute L^2-error and order of convergence without using exact solution.**

**Suppose i don’t know the exact solution then, i want to compute L^2-error and order of convergence .** Infact in lastly, you are setting uhold=ueaxct Which is eaxctly means i know eaxct solution. But this i not want sir. I want that i know only f and u=0 boundary then compute L^2-error and order of convergence.

I sorry, I you do no know the exact solution you car try to computation a good approximation on very very fine mesh, and use this solution as like an exact solution.

My way:

poisson-comp-fine-sol.edp (1.0 KB)