I got this code from a book I bought. I wanted to see if it words but it gives me errors.

Here is the source code.

```
#include<math.h>
#define NRANSI
#include"nrutil.h"
#define SWAP(a,b)
{
temp=(a);(a)=(b);(b)=temp;
}
void gaussj(float **a, int n, float **b, int m)
{
int *indxc,*indxr,*ipiv;
int i,icol,irow,j,k,l,ll;
float big,dum,pivinv,temp;
indxc=ivector(1,n);
indxr=ivector(1,n);
ipiv=ivector(1,n);
for (j=1;j<=n;j++) ipiv[j]=0;
for (i=1;i<=n;i++)
{
big=0.0;
for (j=1;j<=n;j++)
if (ipiv[j] != 1)
for (k=1;k<=n;k++)
{
if (ipiv[k] == 0)
{
if (fabs(a[j][k]) >= big)
{
big=fabs(a[j][k]);
irow=j;
icol=k;
}
}
else if (ipiv[k] > 1) nrerror("gaussj: Singular Matrix-1");
}
++(ipiv[icol]);
if (irow != icol)
{
for (l=1;l<=n;l++) SWAP(a[irow][l],a[icol][l])
for (l=1;l<=m;l++) SWAP(b[irow][l],b[icol][l])
}
indxr[i]=irow;
indxc[i]=icol;
if (a[icol][icol] == 0.0) nrerror("gaussj: Singular Matrix-2");
pivinv=1.0/a[icol][icol];
a[icol][icol]=1.0;
for (l=1;l<=n;l++) a[icol][l] *= pivinv;
for (l=1;l<=m;l++) b[icol][l] *= pivinv;
for (ll=1;ll<=n;ll++)
if (ll != icol)
{
dum=a[ll][icol];
a[ll][icol]=0.0;
for (l=1;l<=n;l++) a[ll][l] -= a[icol][l]*dum;
for (l=1;l<=m;l++) b[ll][l] -= b[icol][l]*dum;
}
}
for (l=n;l>=1;l--)
{
if (indxr[l] != indxc[l])
for (k=1;k<=n;k++)
SWAP(a[k][indxr[l]],a[k][indxc[l]]);
}
free_ivector(ipiv,1,n);
free_ivector(indxr,1,n);
free_ivector(indxc,1,n);
}
#undef SWAP
#undef NRANSI
```

and the header file:

```
#ifndef _NR_UTILS_H_
#define _NR_UTILS_H_
staticfloat sqrarg;
#define SQR(a) ((sqrarg=(a)) == 0.0 ? 0.0 : sqrarg*sqrarg)
staticdouble dsqrarg;
#define DSQR(a) ((dsqrarg=(a)) == 0.0 ? 0.0 : dsqrarg*dsqrarg)
staticdouble dmaxarg1,dmaxarg2;
#define DMAX(a,b) (dmaxarg1=(a),dmaxarg2=(b),(dmaxarg1) > (dmaxarg2) ?\
(dmaxarg1) : (dmaxarg2))
staticdouble dminarg1,dminarg2;
#define DMIN(a,b) (dminarg1=(a),dminarg2=(b),(dminarg1) < (dminarg2) ?\
(dminarg1) : (dminarg2))
staticfloat maxarg1,maxarg2;
#define FMAX(a,b) (maxarg1=(a),maxarg2=(b),(maxarg1) > (maxarg2) ?\
(maxarg1) : (maxarg2))
staticfloat minarg1,minarg2;
#define FMIN(a,b) (minarg1=(a),minarg2=(b),(minarg1) < (minarg2) ?\
(minarg1) : (minarg2))
staticlong lmaxarg1,lmaxarg2;
#define LMAX(a,b) (lmaxarg1=(a),lmaxarg2=(b),(lmaxarg1) > (lmaxarg2) ?\
(lmaxarg1) : (lmaxarg2))
staticlong lminarg1,lminarg2;
#define LMIN(a,b) (lminarg1=(a),lminarg2=(b),(lminarg1) < (lminarg2) ?\
(lminarg1) : (lminarg2))
staticint imaxarg1,imaxarg2;
#define IMAX(a,b) (imaxarg1=(a),imaxarg2=(b),(imaxarg1) > (imaxarg2) ?\
(imaxarg1) : (imaxarg2))
staticint iminarg1,iminarg2;
#define IMIN(a,b) (iminarg1=(a),iminarg2=(b),(iminarg1) < (iminarg2) ?\
(iminarg1) : (iminarg2))
#define SIGN(a,b) ((b) >= 0.0 ? fabs(a) : -fabs(a))
#ifdefined(__STDC__) || defined(ANSI) || defined(NRANSI) /* ANSI */
void nrerror(char error_text[]);
float *vector(long nl, long nh);
int *ivector(long nl, long nh);
unsignedchar *cvector(long nl, long nh);
unsignedlong *lvector(long nl, long nh);
double *dvector(long nl, long nh);
float **matrix(long nrl, long nrh, long ncl, long nch);
double **dmatrix(long nrl, long nrh, long ncl, long nch);
int **imatrix(long nrl, long nrh, long ncl, long nch);
float **submatrix(float **a, long oldrl, long oldrh, long oldcl, long oldch,
long newrl, long newcl);
float **convert_matrix(float *a, long nrl, long nrh, long ncl, long nch);
float ***f3tensor(long nrl, long nrh, long ncl, long nch, long ndl, long ndh);
void free_vector(float *v, long nl, long nh);
void free_ivector(int *v, long nl, long nh);
void free_cvector(unsignedchar *v, long nl, long nh);
void free_lvector(unsignedlong *v, long nl, long nh);
void free_dvector(double *v, long nl, long nh);
void free_matrix(float **m, long nrl, long nrh, long ncl, long nch);
void free_dmatrix(double **m, long nrl, long nrh, long ncl, long nch);
void free_imatrix(int **m, long nrl, long nrh, long ncl, long nch);
void free_submatrix(float **b, long nrl, long nrh, long ncl, long nch);
void free_convert_matrix(float **b, long nrl, long nrh, long ncl, long nch);
void free_f3tensor(float ***t, long nrl, long nrh, long ncl, long nch,
long ndl, long ndh);
#else/* ANSI */
/* traditional - K&R */
void nrerror();
float *vector();
float **matrix();
float **submatrix();
float **convert_matrix();
float ***f3tensor();
double *dvector();
double **dmatrix();
int *ivector();
int **imatrix();
unsignedchar *cvector();
unsignedlong *lvector();
void free_vector();
void free_dvector();
void free_ivector();
void free_cvector();
void free_lvector();
void free_matrix();
void free_submatrix();
void free_convert_matrix();
void free_dmatrix();
void free_imatrix();
void free_f3tensor();
#endif/* ANSI */
#endif/* _NR_UTILS_H_ */
```

The errors I keep on getting is:

1>Linking...

1>gaussj.obj : error LNK2019: unresolved external symbol _free_ivector referenced in function _gaussj

1>gaussj.obj : error LNK2019: unresolved external symbol _nrerror referenced in function _gaussj

1>gaussj.obj : error LNK2019: unresolved external symbol _ivector referenced in function _gaussj

1>LIBCMT.lib(crt0.obj) : error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup

1>C:\Documents\Visual Studio 2005\Projects\Linear Equation\Debug\Linear Equation.exe : fatal error LNK1120: 4 unresolved externals