计算方法之高斯消去

#include "stdio.h" #include "math.h" #include "stdlib.h" typedef double arrtype; //高斯消去法 void GuassScale(arrtype coff[],int n,arrtype *x = NULL,int m = 1) { int col = n + m; arrtype *s = new arrtype[n]; int *nrow = new int[n]; arrtype *base = coff; for(int i = 0; i<n;i++) { s[i] = 0; for(int j = 0;j<n;j++) { arrtype t = fabs(coff[i*col + j]); if(s[i] < t) s[i] = t; } nrow[i] = i; } for(i=0;i<n-1;i++) { int p = i; arrtype t = fabs(coff[nrow[p]*col+i])/s[nrow[p]]; for(int j= i+1;j<n;j++) { arrtype temp= fabs(coff[nrow[j]*col+i])/s[nrow[j]]; if(t<temp) { t=temp; p=j; } } if(coff[nrow[p]*col+i]==0) return; if(nrow[p]!=nrow[i]) { int ncopy = nrow[i]; nrow[i] = nrow[p]; nrow[p] =ncopy; } for(j= i+1;j<n;j++) { arrtype m = coff[nrow[j]*col+i]/coff[nrow[i]*col+i]; for(int k=i+1;k<col;k++) { coff[nrow[j]*col+k]-=coff[nrow[i]*col+k]*m; } } } if(coff[nrow[n-1]*col+n-1]==0) return; for(i=n;i<col;i++) { x[(n-1)*m+(i-n)]=coff[nrow[n-1]*col+i]/coff[nrow[n-1]*col+n-1]; } for(i=n-2;i>=0;i--) { for(int j = n;j<col;j++) { for(int k=n-1;k>i;k--) coff[nrow[i]*col+j]-=coff[nrow[i]*col+k]*x[k*m+(j-n)]; x[i*m+(j-n)]=coff[nrow[i]*col+j]/coff[nrow[i]*col+i]; } } } void main(int argc,char* argv[]) { FILE *fpi,*fpo; if(argc > 1) fpi=fopen(argv[1],"r"); else fpi=stdin; if(!fpi)return; if(argc>2) fpo = fopen(argv[2],"w"); else fpo = stdout; if(!fpo)return; int m,n; printf("请输入ｎ和ｍ的值：/n"); fscanf(fpi,"%d",&n); fscanf(fpi,"%d",&m); arrtype *co; co = new arrtype[n*(n+m)]; for(int i = 0;i<n*(n+m);i++) { float t; fscanf(fpi,"%f",&t); co[i]=t; } fclose(fpi); arrtype *x = new arrtype[m*n]; GuassScale(co,n,x,m); delete[] co; for(i=0;i<n;i++) { fprintf(fpo,"x[%d]=",i); for(int j=0;j<m;j++) fprintf(fpo,"%f",x[i*m+j]); fprintf(fpo,"/n"); } delete[] x; fclose(fpo); }