Getting Numpy array out of PETSc Mat

[jefflarson]

I am trying to get a numpy array out of a PETSc.Mat. For PETSc.Vec objects, b.array does the trick.

But if c is a PETSc.Mat object, getDenseArray() gives the following error

>>> c.getDenseArray()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "Mat.pyx", line 1287, in petsc4py.PETSc.Mat.getDenseArray (src/petsc4py.PETSc.c:122734)
petsc4py.PETSc.Error: error code 56
[0] MatDenseGetArray() line 1499 in /fusion/gpfs/home/jlarson/software/petsc-3.5.3/src/mat/impls/dense/seq/dense.c
[0] No support for this operation for this object type
[0] Cannot locate function MatDenseGetArray_C in object

Is there a way to get the full matrix out?

[Lisandro Dalcin]

What matrix type are you using? Mat.getDenseArray() only works for the MATDENSE matrix type. You have to either convert your matrix to dense format (using c_dense = c.convert("dense")), of in case of a MATAIJ matrix, use ai, aj, av = c.getValuesCSR() to get three arrays in CSR format.

[jefflarson]

Yes. Converting to a dense matrix works. Thank you.