zlaqsy.f

Section: LAPACK (3)
Updated: Tue Nov 14 2017
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NAME

zlaqsy.f  

SYNOPSIS


 

Functions/Subroutines


subroutine zlaqsy (UPLO, N, A, LDA, S, SCOND, AMAX, EQUED)
ZLAQSY scales a symmetric/Hermitian matrix, using scaling factors computed by spoequ.  

Function/Subroutine Documentation

 

subroutine zlaqsy (character UPLO, integer N, complex*16, dimension( lda, * ) A, integer LDA, double precision, dimension( * ) S, double precision SCOND, double precision AMAX, character EQUED)

ZLAQSY scales a symmetric/Hermitian matrix, using scaling factors computed by spoequ.

Purpose: 

 ZLAQSY equilibrates a symmetric matrix A using the scaling factors
 in the vector S.


 

Parameters:

UPLO 

          UPLO is CHARACTER*1
          Specifies whether the upper or lower triangular part of the
          symmetric matrix A is stored.
          = 'U':  Upper triangular
          = 'L':  Lower triangular


N 

          N is INTEGER
          The order of the matrix A.  N >= 0.


A 

          A is COMPLEX*16 array, dimension (LDA,N)
          On entry, the symmetric matrix A.  If UPLO = 'U', the leading
          n by n upper triangular part of A contains the upper
          triangular part of the matrix A, and the strictly lower
          triangular part of A is not referenced.  If UPLO = 'L', the
          leading n by n lower triangular part of A contains the lower
          triangular part of the matrix A, and the strictly upper
          triangular part of A is not referenced.

          On exit, if EQUED = 'Y', the equilibrated matrix:
          diag(S) * A * diag(S).


LDA 

          LDA is INTEGER
          The leading dimension of the array A.  LDA >= max(N,1).


S 

          S is DOUBLE PRECISION array, dimension (N)
          The scale factors for A.


SCOND 

          SCOND is DOUBLE PRECISION
          Ratio of the smallest S(i) to the largest S(i).


AMAX 

          AMAX is DOUBLE PRECISION
          Absolute value of largest matrix entry.


EQUED 

          EQUED is CHARACTER*1
          Specifies whether or not equilibration was done.
          = 'N':  No equilibration.
          = 'Y':  Equilibration was done, i.e., A has been replaced by
                  diag(S) * A * diag(S).


 

Internal Parameters: 

  THRESH is a threshold value used to decide if scaling should be done
  based on the ratio of the scaling factors.  If SCOND < THRESH,
  scaling is done.

  LARGE and SMALL are threshold values used to decide if scaling should
  be done based on the absolute size of the largest matrix element.
  If AMAX > LARGE or AMAX < SMALL, scaling is done.


 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

December 2016

Definition at line 136 of file zlaqsy.f.  

Author

Generated automatically by Doxygen for LAPACK from the source code.

 

Index

NAME
SYNOPSIS
Functions/Subroutines
Function/Subroutine Documentation
subroutine zlaqsy (character UPLO, integer N, complex*16, dimension( lda, * ) A, integer LDA, double precision, dimension( * ) S, double precision SCOND, double precision AMAX, character EQUED)
Author