gf_spmat_get

# Calling Sequence

    n = gf_spmat_get(spmat S, 'nnz')

    Sm = gf_spmat_get(spmat S, 'full'[, list I[, list J]])

    MV = gf_spmat_get(spmat S, 'mult', vec V)

    MtV = gf_spmat_get(spmat S, 'tmult', vec V)

    D = gf_spmat_get(spmat S, 'diag'[, list E])

    s = gf_spmat_get(spmat S, 'storage')

    {ni,nj} = gf_spmat_get(spmat S, 'size')

    b = gf_spmat_get(spmat S, 'is_complex')

    {JC, IR} = gf_spmat_get(spmat S, 'csc_ind')

    V = gf_spmat_get(spmat S, 'csc_val')

    {N, U0} = gf_spmat_get(spmat S, 'dirichlet nullspace', vec R)

    gf_spmat_get(spmat S, 'save', string format, string filename)

    s = gf_spmat_get(spmat S, 'char')

    gf_spmat_get(spmat S, 'display')

## Description

## Command list

- `n = gf_spmat_get(spmat S, 'nnz')`

  Return the number of non-null values stored in the sparse matrix.

- `Sm = gf_spmat_get(spmat S, 'full'[, list I[, list J]])`

  Return a full (sub-)matrix. The optional arguments `I` and `J`, are the sub-intervals for the rows and columns that are to be extracted.

- `MV = gf_spmat_get(spmat S, 'mult', vec V)`

  Product of the sparse matrix `M` with a vector `V`. For matrix-matrix multiplications, see gf_spmat('mult').

- `MtV = gf_spmat_get(spmat S, 'tmult', vec V)`

  Product of `M` transposed (conjugated if `M` is complex) with the vector `V`.

- `D = gf_spmat_get(spmat S, 'diag'[, list E])`

  Return the diagonal of `M` as a vector. If `E` is used, return the sub-diagonals whose ranks are given in E.

- `s = gf_spmat_get(spmat S, 'storage')`

  Return the storage type currently used for the matrix. The storage is returned as a string, either 'CSC' or 'WSC'.

- `{ni,nj} = gf_spmat_get(spmat S, 'size')`

  Return a vector where `ni` and `nj` are the dimensions of the matrix.

- `b = gf_spmat_get(spmat S, 'is_complex')`

  Return 1 if the matrix contains complex values.

- `{JC, IR} = gf_spmat_get(spmat S, 'csc_ind')`

  Return the two usual index arrays of CSC storage. If `M` is not stored as a CSC matrix, it is converted into CSC.

- `V = gf_spmat_get(spmat S, 'csc_val')`

  Return the array of values of all non-zero entries of `M`. If `M` is not stored as a CSC matrix, it is converted into CSC.

- `{N, U0} = gf_spmat_get(spmat S, 'dirichlet nullspace', vec R)`

  Solve the dirichlet conditions `M.U=R`. A solution `U0` which has a minimum L2-norm is returned, with a sparse matrix `N` containing an orthogonal basis of the kernel of the (assembled) constraints matrix `M` (hence, the PDE linear system should be solved on this subspace): the initial problem `K.U = B` with constraints `M.U = R` is replaced by `(N'.K.N).UU = N'.B` with `U = N.UU + U0`

- `gf_spmat_get(spmat S, 'save', string format, string filename)`

  Export the sparse matrix. the format of the file may be 'hb' for Harwell-Boeing, or 'mm' for Matrix-Market.

- `s = gf_spmat_get(spmat S, 'char')`

  Output a (unique) string representation of the spmat. This can be used to perform comparisons between two different spmat objects. This function is to be completed.

- `gf_spmat_get(spmat S, 'display')`

  displays a short summary for a spmat object.

## See Also

- getfem types

## Authors

Y. Collette