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/* Copyright (C) 2017 - IIT Bombay - FOSSEE
This file must be used under the terms of the CeCILL.
This source file is licensed as described in the file COPYING, which
you should have received as part of this distribution. The terms
are also available at
http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
Author: Siddhesh Wani
Organization: FOSSEE, IIT Bombay
Email: toolbox@scilab.in
*/
/*Funtion to find inverse condition number of square matrix*/
#include "lapack.h"
#include "stdlib.h"
#include "string.h"
double drconda(double* in1, int rows)
{
double *buf, *IPIV, *LDWORK, *LIWORK;
int INFO;
char one = '1';
double ANORM;
double RCOND = 1;
buf = (double*) malloc((double) rows*rows*sizeof(double));
IPIV = (double*) malloc((double) rows*sizeof(double));
LIWORK = (double*) malloc((double) rows*sizeof(double));
LDWORK = (double*) malloc((double) 4*rows*sizeof(double));
/*Copy input in temp buf, as lapack modifies input*/
memcpy(buf,in1,rows*rows*sizeof(double));
ANORM = dlange_(&one,&rows,&rows,buf,&rows,LDWORK);
dgetrf_(&rows,&rows,buf,&rows,IPIV,&INFO);
if(INFO == 0)
{
dgecon_(&one,&rows,buf,&rows,&ANORM,&RCOND,LDWORK,LIWORK,&INFO);
}
return RCOND;
}
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