This information is part of the Modelica Standard Library maintained by the Modelica Association.

Syntax

         H = Matrices.cholesky(A);
         H = Matrices.cholesky(A, upper=true);
 

Description

Function cholesky computes the Cholesky factorization of a real symmetric positive definite matrix A. The optional Boolean input "upper" specifies whether the upper or the lower triangular matrix is returned, i.e.

 A = H'*H   if upper is true (H is upper triangular)
 A = H*H'   if upper is false (H is lower triangular)

The computation is performed by LAPACK.dpotrf.

Example

  A  = [1, 0,  0;
        6, 5,  0;
        1, -2,  2];
  S = A*transpose(A);

  H = Matrices.cholesky(S);

  results in:

  H = [1.0,  6.0,  1.0;
       0.0,  5.0, -2.0;
       0.0,  0.0,  2.0]

  with

  transpose(H)*H = [1.0,  6.0,   1;
                    6.0, 61.0,  -4.0;
                    1.0, -4.0,   9.0] //=S

H = cholesky(A, upper)

A	Type: Real[:,size(A, 1)] Description: Symmetric positive definite matrix
upper	Default Value: true Type: Boolean Description: True if the right cholesky factor (upper triangle) should be returned

H	Type: Real[size(A, 1),size(A, 2)] Description: Cholesky factor U (upper=true) or L (upper=false) for A = U'*U or A = L*L'