#include "stdlib.h"
#include "stdio.h"
int cgas(ar,ai,n,br,bi)
int n;
double ar[],ai[],br[],bi[];
{ 
	int *js,l,k,i,j,is,u,v;
	double p,q,s,d;
	js=malloc(n*sizeof(int));
	for (k=0;k<=n-2;k++)
	{	 
		d=0.0;
		for (i=k;i<=n-1;i++)
		for (j=k;j<=n-1;j++)
		{ 
			u=i*n+j;
			p=ar[u]*ar[u]+ai[u]*ai[u];
			if (p>d) 
			{
				d=p;js[k]=j;is=i;
			}
		}
		if (d+1.0==1.0)
		{ 
			free(js); 
			printf("err**fail\n");
			return(0);
		}
		if (is!=k)
		{ 
			for (j=k;j<=n-1;j++)
			{ 
				u=k*n+j; v=is*n+j;
				p=ar[u]; ar[u]=ar[v]; ar[v]=p;
				p=ai[u]; ai[u]=ai[v]; ai[v]=p;
			}
			p=br[k]; br[k]=br[is]; br[is]=p;
			p=bi[k]; bi[k]=bi[is]; bi[is]=p;
		}
		if (js[k]!=k)
		{
			for (i=0;i<=n-1;i++)
			{ 
				u=i*n+k; v=i*n+js[k];
				p=ar[u]; ar[u]=ar[v]; ar[v]=p;
				p=ai[u]; ai[u]=ai[v]; ai[v]=p;
			}
		}
		v=k*n+k;
		for (j=k+1;j<=n-1;j++)
		{ 
			u=k*n+j;
			p=ar[u]*ar[v]; q=-ai[u]*ai[v];
			s=(ar[v]-ai[v])*(ar[u]+ai[u]);
			ar[u]=(p-q)/d; ai[u]=(s-p-q)/d;
		}
		p=br[k]*ar[v]; q=-bi[k]*ai[v];
		s=(ar[v]-ai[v])*(br[k]+bi[k]);
		br[k]=(p-q)/d; bi[k]=(s-p-q)/d;
		for (i=k+1;i<=n-1;i++)
		{ 
			u=i*n+k;
			for (j=k+1;j<=n-1;j++)
			{ 
				v=k*n+j; l=i*n+j;
				p=ar[u]*ar[v]; q=ai[u]*ai[v];
				s=(ar[u]+ai[u])*(ar[v]+ai[v]);
				ar[l]=ar[l]-p+q;
				ai[l]=ai[l]-s+p+q;
			}
			p=ar[u]*br[k]; q=ai[u]*bi[k];
			s=(ar[u]+ai[u])*(br[k]+bi[k]);
			br[i]=br[i]-p+q; bi[i]=bi[i]-s+p+q;
		}
	}
	u=(n-1)*n+n-1;
	d=ar[u]*ar[u]+ai[u]*ai[u];
	if (d+1.0==1.0)
	{ 
		free(js); 
		printf("err**fail\n");
		return(0);
	}
	p=ar[u]*br[n-1]; q=-ai[u]*bi[n-1];
	s=(ar[u]-ai[u])*(br[n-1]+bi[n-1]);
	br[n-1]=(p-q)/d; bi[n-1]=(s-p-q)/d;
	for (i=n-2;i>=0;i--)
		for (j=i+1;j<=n-1;j++)
		{ 
			u=i*n+j;
			p=ar[u]*br[j]; q=ai[u]*bi[j];
			s=(ar[u]+ai[u])*(br[j]+bi[j]);
			br[i]=br[i]-p+q;
			bi[i]=bi[i]-s+p+q;
		}
	js[n-1]=n-1;
	for (k=n-1;k>=0;k--)
	{
		if (js[k]!=k)
		{ 
			p=br[k]; br[k]=br[js[k]]; br[js[k]]=p;
			p=bi[k]; bi[k]=bi[js[k]]; bi[js[k]]=p;
		}
	}
	free(js);
	return(1);
}