Description of set

set_diagonal		Programmers Guide
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Category:algorithms

Component type:function

Prototype

template <class Matrix, class T> void set_diagonal(Matrix& A, const T& alpha) ;

Description

Set the value of the elements on the main diagonal of A to alpha.

Definition

mtl.h

Requirements on types

T must be convertible to Matrix::value_type.

Preconditions

Complexity

O(min(m,n)) for dense matrices, O(nnz) for sparse matrices (except envelope, which is O(m))

Example

In tri_pack_sol.cc:

  const int N = 4;
  Matrix A(N, N);

  set_diagonal(A, 1);

  //C         1.0                         8.0
  //C     A = 2.0  1.0              b =  25.0
  //C         3.0  5.0  1.0              79.0
  //C         4.0  6.0  7.0  1.0        167.0

  A(1,0) = 2; A(2,1) = 5; A(3,2) = 7;
  A(2,0) = 3; A(3,1) = 6;
  A(3,0) = 4;

Notes

See also