[petsc-users] Matricize a vector

[elam at cs.toronto.edu]

Hello,

Is it possible to reshape a vector into a matrix in PETSc?  I need to do
this to compute a matrix vector multiplication (Ax) where the matrix A can
be decomposed into Kronecker tensor format.  For example, A = A1 kron A2
kron A3, where A1, A2, A3 are smaller sparse matrices.

Essentially, I need to matricize the vector x and perform a series of
matrix matrix multiplications to compute Ax.  In Matlab the function to
perform the matricization is reshape.  Is there a similar function in
PETSc?

I could implement the (tensor product) matrix vector multiplication by
creating temporary matrices to store each of the intermediate matrix
matrix multiplication results.  But this seems inefficient.  I was
wondering if there is a more efficient way to implement this in PETSc? 
Can I simply reset the size of a matrix (as long as the number of elements
remain the same) to reshape it?  Any suggestions would be appreciated.

Thank you for your help.

Best regards,

Elizabeth