scipy tutorial - Baustatik-Info-Server

spdiags(data, diags, m, n, format=None)
Return a sparse matrix from diagonals.
See Also:
Parameters
data : array_like
matrix diagonals stored row-wise
diags : diagonals to set
• k = 0 the main diagonal
• k > 0 the k-th upper diagonal
• k < 0 the k-th lower diagonal
m, n : int
shape of the result
format : format of the result (e.g. “csr”)
SciPy Reference Guide, Release 0.8.dev
By default (format=None) an appropriate sparse matrix format is returned. This
choice is subject to change.
dia_matrix
the sparse DIAgonal format.
Examples
>>> data = array([[1,2,3,4],[1,2,3,4],[1,2,3,4]])
>>> diags = array([0,-1,2])
>>> spdiags(data, diags, 4, 4).todense()
matrix([[1, 0, 3, 0],
[1, 2, 0, 4],
[0, 2, 3, 0],
[0, 0, 3, 4]])
tril(A, k=0, format=None)
Return the lower triangular portion of a matrix in sparse format
Returns the elements on or below the k-th diagonal of the matrix A.
• k = 0 corresponds to the main diagonal
• k > 0 is above the main diagonal
• k < 0 is below the main diagonal
Parameters
A : dense or sparse matrix
Matrix whose lower trianglar portion is desired.
k : integer
The top-most diagonal of the lower triangle.
format : string
Sparse format of the result, e.g. format=”csr”, etc.
3.14. Sparse matrices (scipy.sparse) 387