dgscon.c File Reference

Estimates reciprocal of the condition number of a general matrix. More...

`#include <math.h>`
`#include "slu_ddefs.h"`
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## Functions

void | dgscon (char *norm, SuperMatrix *L, SuperMatrix *U, double anorm, double *rcond, SuperLUStat_t *stat, int *info)

## Detailed Description

Copyright (c) 2003, The Regents of the University of California, through Lawrence Berkeley National Laboratory (subject to receipt of any required approvals from U.S. Dept. of Energy)

All rights reserved.

The source code is distributed under BSD license, see the file License.txt at the top-level directory.

    -- SuperLU routine (version 7.0.0) --
    Univ. of California Berkeley, Xerox Palo Alto Research Center,
    and Lawrence Berkeley National Lab.
    July 25, 2015
    August 2024

    Modified from lapack routines DGECON.

## Function Documentation

## dgscon()

void dgscon | ( | char * | norm,
|  | SuperMatrix * | L,
|  | SuperMatrix * | U,
|  | double | anorm,
|  | double * | rcond,
|  | SuperLUStat_t * | stat,
|  | int * | info
| ) |  |

      Purpose
      =======

      DGSCON estimates the reciprocal of the condition number of a general
      real matrix A, in either the 1-norm or the infinity-norm, using
      the LU factorization computed by DGSTRF.   *

      An estimate is obtained for norm(inv(A)), and the reciprocal of the
      condition number is computed as
         RCOND = 1 / ( norm(A) * norm(inv(A)) ).

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

      Arguments
      =========

       NORM    (input) char*
               Specifies whether the 1-norm condition number or the
               infinity-norm condition number is required:
               = '1' or 'O':  1-norm;
               = 'I':         Infinity-norm.

       L       (input) SuperMatrix*
               The factor L from the factorization Pr*A*Pc=L*U as computed by
               dgstrf(). Use compressed row subscripts storage for supernodes,
               i.e., L has types: Stype = SLU_SC, Dtype = SLU_D, Mtype = SLU_TRLU.

       U       (input) SuperMatrix*
               The factor U from the factorization Pr*A*Pc=L*U as computed by
               dgstrf(). Use column-wise storage scheme, i.e., U has types:
               Stype = SLU_NC, Dtype = SLU_D, Mtype = SLU_TRU.

       ANORM   (input) double
               If NORM = '1' or 'O', the 1-norm of the original matrix A.
               If NORM = 'I', the infinity-norm of the original matrix A.

       RCOND   (output) double*
              The reciprocal of the condition number of the matrix A,
              computed as RCOND = 1/(norm(A) * norm(inv(A))).

       INFO    (output) int*
              = 0:  successful exit
              < 0:  if INFO = -i, the i-th argument had an illegal value

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

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