///正确的高斯全选项主元消去法
#include <cstdlib>
#include <iostream>
#include <math.h>
#include <fstream>
using namespace std;
int mygauss(double *allm,int n,double * b)
{
ofstream resultfile("result.out");
int * js,l,k,i,j,is,p,q;
double d,t;
js=(int *)malloc(n*sizeof(int));
l=1;//置非奇异标志
//cout<<"hui";
for(k=0;k<=n-2;k++)
{
d=0.0;
for(i=k;i<=n-1;i++)
for(j=k;j<=n-1;j++)
{
t=fabs(allm[i*n+j]);
if(t>d){d=t;js[k]=j;is=i;};//记忆行列交换信息,,,js[k]保存列
}
//cout<<d<<'#';
//cout<<js[k]<<'@';
// cout<<"i"<<is;
if(d+1.0==1.0)l=0;
else
{
if(js[k]!=k)
{
for(i=0;i<=n-1;i++) //列交换
{
p=i*n+k;q=i*n+js[k];
t=allm[p];allm[p]=allm[q];allm[q]=t;
}
}
if(is!=k)//行交换
{
for(j=k;j<=n-1;j++)
{
p=k*n+j;q=is*n+j;
t=allm[p];allm[p]=allm[q];allm[q]=t;
}
t=b[k];b[k]=b[is];b[is]=t;
}
}
if(l==0)//奇异返回
{
free(js);printf("fail/n"); return 0;
}
d=allm[k*n+k];
for(j=k+1;j<=n-1;j++)//归一化
{p=k*n+j;allm[p]=allm[p]/d;}
b[k]=b[k]/d;
for(i=k+1;i<=n-1;i++)//消元
{
for(j=k+1;j<=n-1;j++)
{
p=i*n+j;
allm[p]=allm[p]-allm[i*n+k]*allm[k*n+j];
}
b[i]=b[i] -allm[i*n+k]*b[k];
}
//for(int w=0;w<n;w++)
//{
//for(int y=0;y<n;y++)
//{
// cout<<allm[w*n+y]<<'#';
// }
// cout<<endl;
//}
}
d=allm[(n-1)*n+n-1];
if(fabs(d)+1.0==1.0)//奇异返回
{
free(js);printf("fail/n");
return 0;
}
b[n-1]=b[n-1]/d;
for(i=n-2;i>=0;i--)
{
t=0.0;
for(j=i+1;j<=n-1;j++)
t=t+allm[i*n+j]*b[j];
b[i]=b[i]-t;
}
js[n-1]=n-1;
for(k=n-1;k>=0;k--)
{
if(js[k]!=k)
{
t=b[k];b[k]=b[js[k]];b[js[k]]=t;
}
}
for(int pos=0;pos<n;pos++)
{
//cout<<b[pos]<<"flag";
resultfile<<b[pos];
resultfile<<'/n';
}
free(js);
resultfile.close();
return 1;
}
int main(int argc, char *argv[])
{
double * dall;
double a[16]={0.2368,0.2471,0.2568,1.2671,
0.1968,0.2071,1.2168,0.2271,
0.1581,1.1675,0.1768,0.1871,
1.1161,0.1254,0.1397,0.1490};
dall=a;
double * djg;
double jga[4]={1.8471,1.7471,1.6471,1.5471};
djg=jga;
mygauss(dall,4,djg);
system("PAUSE");
return EXIT_SUCCESS;
}
//result.out
1.04058
0.987051
0.93504
0.881282
