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<title>SuperLU: SRC/dgsequ.c File Reference</title>
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    SRC/dgsequ.c File Reference

    Computes row and column scalings. More...
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    #include <math.h>
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    #include "slu_ddefs.h"
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    Functions

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    void dgsequ (SuperMatrix *A, double *r, double *c, double *rowcnd, double *colcnd, double *amax, int *info)
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     Driver related.  
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    Detailed Description

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     -- SuperLU routine (version 2.0) --
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     Univ. of California Berkeley, Xerox Palo Alto Research Center,
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     and Lawrence Berkeley National Lab.
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     November 15, 1997

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     Modified from LAPACK routine DGEEQU
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    Function Documentation

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              void dgsequ           
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              (
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              SuperMatrix
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               A, 
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              double * 
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               r, 
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              double * 
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               c, 
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              double * 
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               rowcnd, 
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              double * 
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               colcnd, 
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              double * 
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               amax, 
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              int * 
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               info 
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              )
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     Purpose   
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       =======

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       DGSEQU computes row and column scalings intended to equilibrate an   
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       M-by-N sparse matrix A and reduce its condition number. R returns the row
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       scale factors and C the column scale factors, chosen to try to make   
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       the largest element in each row and column of the matrix B with   
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       elements B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1.

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       R(i) and C(j) are restricted to be between SMLNUM = smallest safe   
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       number and BIGNUM = largest safe number.  Use of these scaling   
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       factors is not guaranteed to reduce the condition number of A but   
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       works well in practice.

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       See supermatrix.h for the definition of 'SuperMatrix' structure.

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       Arguments   
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       =========

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       A       (input) SuperMatrix*
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               The matrix of dimension (A->nrow, A->ncol) whose equilibration
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               factors are to be computed. The type of A can be:
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               Stype = SLU_NC; Dtype = SLU_D; Mtype = SLU_GE.

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       R       (output) double*, size A->nrow
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               If INFO = 0 or INFO > M, R contains the row scale factors   
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               for A.

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       C       (output) double*, size A->ncol
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               If INFO = 0,  C contains the column scale factors for A.

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       ROWCND  (output) double*
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               If INFO = 0 or INFO > M, ROWCND contains the ratio of the   
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               smallest R(i) to the largest R(i).  If ROWCND >= 0.1 and   
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               AMAX is neither too large nor too small, it is not worth   
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               scaling by R.

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       COLCND  (output) double*
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               If INFO = 0, COLCND contains the ratio of the smallest   
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               C(i) to the largest C(i).  If COLCND >= 0.1, it is not   
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               worth scaling by C.

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       AMAX    (output) double*
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               Absolute value of largest matrix element.  If AMAX is very   
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               close to overflow or very close to underflow, the matrix   
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               should be scaled.

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       INFO    (output) int*
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               = 0:  successful exit   
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               < 0:  if INFO = -i, the i-th argument had an illegal value   
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               > 0:  if INFO = i,  and i is   
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                     <= A->nrow:  the i-th row of A is exactly zero   
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                     >  A->ncol:  the (i-M)-th column of A is exactly zero

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       ===================================================================== 
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