DLAQGE(1) LAPACK auxiliary routine (version 3.2) DLAQGE(1)NAME
DLAQGE - equilibrates a general M by N matrix A using the row and col‐
umn scaling factors in the vectors R and C
SYNOPSIS
SUBROUTINE DLAQGE( M, N, A, LDA, R, C, ROWCND, COLCND, AMAX, EQUED )
CHARACTER EQUED
INTEGER LDA, M, N
DOUBLE PRECISION AMAX, COLCND, ROWCND
DOUBLE PRECISION A( LDA, * ), C( * ), R( * )
PURPOSE
DLAQGE equilibrates a general M by N matrix A using the row and column
scaling factors in the vectors R and C.
ARGUMENTS
M (input) INTEGER
The number of rows of the matrix A. M >= 0.
N (input) INTEGER
The number of columns of the matrix A. N >= 0.
A (input/output) DOUBLE PRECISION array, dimension (LDA,N)
On entry, the M by N matrix A. On exit, the equilibrated
matrix. See EQUED for the form of the equilibrated matrix.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(M,1).
R (input) DOUBLE PRECISION array, dimension (M)
The row scale factors for A.
C (input) DOUBLE PRECISION array, dimension (N)
The column scale factors for A.
ROWCND (input) DOUBLE PRECISION
Ratio of the smallest R(i) to the largest R(i).
COLCND (input) DOUBLE PRECISION
Ratio of the smallest C(i) to the largest C(i).
AMAX (input) DOUBLE PRECISION
Absolute value of largest matrix entry.
EQUED (output) CHARACTER*1
Specifies the form of equilibration that was done. = 'N': No
equilibration
= 'R': Row equilibration, i.e., A has been premultiplied by
diag(R). = 'C': Column equilibration, i.e., A has been post‐
multiplied by diag(C). = 'B': Both row and column equilibra‐
tion, i.e., A has been replaced by diag(R) * A * diag(C).
PARAMETERS
THRESH is a threshold value used to decide if row or column scaling
should be done based on the ratio of the row or column scaling factors.
If ROWCND < THRESH, row scaling is done, and if COLCND < THRESH, column
scaling is done. LARGE and SMALL are threshold values used to decide
if row scaling should be done based on the absolute size of the largest
matrix element. If AMAX > LARGE or AMAX < SMALL, row scaling is done.
LAPACK auxiliary routine (versioNovember 2008 DLAQGE(1)