数值分析上机C语言代码.zip_三次样条插值_数值分析C语言编程上机实验

#include<stdio.h> #include<math.h> #define N 9//方程组阶数 typedef double s32; int main() { static s32 a[N][N]={{12.38412,2.115237,-1.061074,1.112336,-0.113584,0.718719,1.742382,3.067813,-2.031743}, {2.115237,19.141823,-3.125432,-1.012345,2.189736,1.563849,-0.784165,1.112348,3.123124}, {-1.061074,-3.125432,15.567914,3.123848,2.031454,1.836742,-1.056781,0.336993,-1.010103}, {1.112336,-1.012345,3.123848,27.108437,4.101011,-3.741856,2.101023,-0.71828,-0.037585}, {-0.113584,2.189736,2.031454,4.101011,19.897918,0.431637,-3.111223,2.121314,1.784317}, {0.718719,1.563849,1.836742,-3.741856,0.431637,9.789365,-0.103458,-1.103456,0.238417}, {1.742382,-0.784165,-1.056781,2.101023,-3.111223,-0.103458,14.7138465,3.123789,-2.213474}, {3.067813,1.112348,0.336993,-0.71828,2.121314,-1.103456,3.123789,30.719334,4.446782}, {-2.031743,3.123124,-1.010103,-0.037585,1.784317,0.238417,-2.213474,4.446782,40.00001} }; s32 b[N]={2.1874369,33.992318,-25.173417,0.84671695,1.784317,-86.612343,1.1101230,4.719345,-5.6784392}; s32 x[N]={0,0,0,0,0,0,0,0,0}; s32 r,s,e; int k,i,j,p,flag=1; printf("\n****高斯列主消元法****\n\n"); for(k=0;k<N-1;k++) { p=k; e=a[k][k]; for(i=k;i<N;i++) if(fabs(a[i][k])>e)//找主元 { e=fabs(a[i][k]); p=i; } for(j=k;j<N;j++) { s=a[k][j];//交换两行 a[k][j]=a[p][j]; a[p][j]=s; } s=b[k]; b[k]=b[p]; b[p]=s; if(a[k][k]==0) { printf("列主消元程序不能运行。"); flag=0; break; } else { for(i=k+1;i<N;i++) { r=a[i][k]/a[k][k]; if(a[k][k]!=0) { for(j=k;j<N;j++) a[i][j]=a[i][j]-r*a[k][j];//进行消元计算 } b[i]=b[i]-r*b[k]; } } } if(flag) { x[N-1]=b[N-1]/a[N-1][N-1];//回代过程 for(i=N-2;i>=0;i--) { s=b[i]; for(j=i+1;j<N;j++) s=s-a[i][j]*x[j]; x[i]=s/a[i][i]; } for(i=0;i<N;i++) printf("x[%d]=%10.7f\n",i+1,x[i]); } }