human
I am working on the file ".ipynb_checkpoints/Making_a_Preconditioner-checkpoint.ipynb".
The first task is:
The nested function is required because "matvec" in LinearOperator takes only one argument-- the vector. But we require the grid details and boundary condition information to create the Poisson matrix. Now will use these to solve a problem. Unlike earlier where we used an analytical solution and RHS, we will start with a random vector which will be our exact solution, and multiply it with the Poisson matrix to get the Rhs vector for the problem. There is no analytical equation associated with the matrix equation. 
The scipy sparse solve routines do not return the number of iterations performed. We can use this wrapper to get the number of iterations
Can you write Python code for it?
 ... Give me a the Python code you requested?
assistant
#Here is the Python code you requested.

def solve_sparse(solver,A, b,tol=1e-10,maxiter=500,M=None):
      num_iters = 0
      def callback(xk):
         nonlocal num_iters
         num_iters+=1
      x,status=solver(A, b,tol=tol,maxiter=maxiter,callback=callback,M=M)
      return x,status,num_iters