A little tougher to track down than I thought, but you are missing a couple of steps: P = scipy.sparse.linalg.spilu(matrix, fill_factor=int(math.sqrt(m))) M_x = lambda x: P.solve(x) M = scipy.sparse.linalg.LinearOperator((n * m, n * m), M_x) #(n*m,n*m)==matrix shape result = scipy.sparse.linalg.lgmres(matrix, b, tol=1e-5, M=M) On 11/20/2015 2:37 AM, Puiseux Pierre wrote:

Hello,

i try to solve a linear sparse system using scipy.sparse.linalg.gmres.

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w, v = gmres(A, b)

It works fine.

Now i’m trying to improve the iterations, using scipy.sparse.linalg.spilu preconditionner :

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invA = spilu(A)

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w,v = gmres(A, b, M=invA)

File "<string>", line 2, in gmres File "/usr/local/lib/python2.7/site-packages/scipy/sparse/linalg/isolve/iterative.py", line 85, in non_reentrant return func(*a, **kw) File "/usr/local/lib/python2.7/site-packages/scipy/sparse/linalg/isolve/iterative.py", line 422, in gmres A,M,x,b,postprocess = make_system(A,M,x0,b,xtype) File "/usr/local/lib/python2.7/site-packages/scipy/sparse/linalg/isolve/utils.py", line 131, in make_system M = aslinearoperator(M) File "/usr/local/lib/python2.7/site-packages/scipy/sparse/linalg/interface.py", line 682, in aslinearoperator raise TypeError('type not understood') TypeError: type not understood

Do i mistake somewhere ?

Thanks for your answer.

Pierre Puiseux

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