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## [Bug-gsl] [GSL]: bug?

 From: James W. Haefner Subject: [Bug-gsl] [GSL]: bug? Date: Wed, 03 Dec 2003 12:25:40 -0700 User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030701

There seems to be a problem with the unweighted linear regression function. The following gives the wrong value for the slope. If I'm misusing it, please let me know.
```
--
James W. Haefner             Email: address@hidden
Dept Biology/Ecology Center  Voice: 435-797-3553
Utah State University        FAX:   435-797-1575
Logan, UT 84322-5305

=========================================================
/* tgsl_reg.c -- test GSL linear regression function */
/* header files */
#include <stdio.h>
#include <ctype.h>
#include <stdarg.h>
#include <string.h>
#include <math.h>

#include <gsl/gsl_errno.h>
#include <gsl/gsl_matrix.h>
#include <gsl/gsl_vector.h>
#include <gsl/gsl_odeiv.h>
#include <gsl/gsl_fit.h>

int main()
{
int i;
double c0,c1;  /* int and slope */
double c00,c01,c11; /* var-covar elemnts for parameters*/
double chisq;
/* y = 2 + 10*x */
double x[]={0,1,2,3,4,5,6};
double y[]={2,12,22,32,42,52,62};
i=gsl_fit_linear(x,(const size_t)1,y,(const size_t)1,(size_t)7,
&c0,&c1,&c00,&c01,&c1,&chisq);
printf(" c0=%f c1=%f  c00=%f c01=%f c00=%f chisq=%f\n",
c0,c1,c00,c01,c11,chisq);
return 0;
}

```

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