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Operators and Keywords

Function List:

C++ API

: B = spdiags (A)
: [B, d] = spdiags (A)
: B = spdiags (A, d)
: A = spdiags (v, d, A)
: A = spdiags (v, d, m, n)

A generalization of the function diag.

Called with a single input argument, the nonzero diagonals d of A are extracted.

With two arguments the diagonals to extract are given by the vector d.

The other two forms of spdiags modify the input matrix by replacing the diagonals. They use the columns of v to replace the diagonals represented by the vector d. If the sparse matrix A is defined then the diagonals of this matrix are replaced. Otherwise a matrix of m by n is created with the diagonals given by the columns of v.

Negative values of d represent diagonals below the main diagonal, and positive values of d diagonals above the main diagonal.

For example: 

spdiags (reshape (1:12, 4, 3), [-1 0 1], 5, 4)
   ⇒ 5 10  0  0
      1  6 11  0
      0  2  7 12
      0  0  3  8
      0  0  0  4

See also: diag.

Package: octave