|void||dlaqgs (SuperMatrix *A, double *r, double *c, double rowcnd, double colcnd, double amax, char *equed)|
-- SuperLU routine (version 2.0) -- Univ. of California Berkeley, Xerox Palo Alto Research Center, and Lawrence Berkeley National Lab. November 15, 1997
Modified from LAPACK routine DLAQGE
|#define THRESH (0.1)|
|void dlaqgs||(||SuperMatrix *||A,|
DLAQGS equilibrates a general sparse M by N matrix A using the row and scaling factors in the vectors R and C.
See supermatrix.h for the definition of 'SuperMatrix' structure.
A (input/output) SuperMatrix* On exit, the equilibrated matrix. See EQUED for the form of the equilibrated matrix. The type of A can be: Stype = NC; Dtype = SLU_D; Mtype = GE.
R (input) double*, dimension (A->nrow) The row scale factors for A.
C (input) double*, dimension (A->ncol) The column scale factors for A.
ROWCND (input) double Ratio of the smallest R(i) to the largest R(i).
COLCND (input) double Ratio of the smallest C(i) to the largest C(i).
AMAX (input) double Absolute value of largest matrix entry.
EQUED (output) char* 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 postmultiplied by diag(C). = 'B': Both row and column equilibration, i.e., A has been replaced by diag(R) * A * diag(C).
Internal 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.