SRC/cgscon.c File Reference

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

#include <math.h>
#include "slu_cdefs.h"

Functions
void	cgscon (char *norm, SuperMatrix *L, SuperMatrix *U, float anorm, float *rcond, SuperLUStat_t *stat, int *info)

---

Detailed Description

 -- SuperLU routine (version 3.0) --
 Univ. of California Berkeley, Xerox Palo Alto Research Center,
 and Lawrence Berkeley National Lab.
 October 15, 2003

 Modified from lapack routines CGECON.
 

---

Function Documentation

void cgscon	(	char *	norm,
		SuperMatrix *	L,
		SuperMatrix *	U,
		float	anorm,
		float *	rcond,
		SuperLUStat_t *	stat,
		int *	info
	)

   Purpose   
   =======

   CGSCON 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 CGETRF.   *

   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
            cgstrf(). Use compressed row subscripts storage for supernodes,
            i.e., L has types: Stype = SLU_SC, Dtype = SLU_C, Mtype = SLU_TRLU.

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

    ANORM   (input) float
            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) float*
           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

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