main.c

/// /求一般矩阵的特征根的算法与C程序

  #include<stdio.h>  
  #include   <math.h>   
  #include   <malloc.h>   
  #include   "lib\elmhes.h"   
  #include   "lib\hqr.h"   
  #define    N   3   
    
  void   main()   
  {   
  double   b[N+1][N+1]={{0,0,0,0},{0,3,1,-1},{0,2,2,-1},{0,2,2,0}};/*这里矩阵无需对称,若对称,则特征值均为实数*/   
  double   **a;   
  double   wr[N+1],wi[N+1];/*特征值的实部和虚部*/   
  int   i,j;   
  a=(double   **)   malloc((unsigned)   (N+1)*sizeof(double*));   
  for(i=0;i<=N;i++)   
  a[i]=b[i];   /*赋值完毕*/   
    
  printf("Original   A:\n");   
  for(i=1;i<=N;i++)   
  {   
  for(j=1;j<=N;j++)   
  printf("%f     ",a[i][j]);   
  printf("\n");   
  }   
    
    
  elmhes(a,N);   /*变换至上Hessenburg型,特征值不变*/   
  printf("After   Elmhes:\n");   
  for(i=1;i<=N;i++)   
  for(j=1;j<(i-1);j++)   
  a[i][j]=0;   
    
  for(i=1;i<=N;i++)   
  {   
  for(j=1;j<=N;j++)   
  printf("%f     ",a[i][j]);   
  printf("\n");   
  }   
    
  
  hqr(a,N,wr,wi);/*用QR方法求上Hessenburg型矩阵的特征值 */ 
  printf("Eigenvalue:\n");   
  for(i=1;i<=N;i++)   
  printf("%f   +   %f   *   i\n",wr[i],wi[i]);  
 
}