elr20.c

数值分析算法描述与习题解答

  #include "stdio.h"
  #include "elr2.c"
  main()
  { int i,j;
    double t,h,eps,y[3];
    void  elr2f();
    y[0]=-1.0; y[1]=0.0; y[2]=1.0;
    t=0.0; h=0.01; eps=0.00001;
    printf("\n");
    printf("t=%5.2f\n",t);
    for (i=0; i<=2; i++)
      printf("y(%d)=%e  ",i,y[i]);
    printf("\n");
    for (j=1; j<=10; j++)
      { elr2(t,h,y,3,eps,elr2f);
        t=t+h;
        printf("t=%5.2f\n",t);
        for (i=0; i<=2; i++)
          printf("y(%d)=%e  ",i,y[i]);
        printf("\n");
      }
  }

  void elr2f(t,y,n,d)
  int n;
  double t,y[],d[];
  { t=t; n=n;
    d[0]=y[1]; d[1]=-y[0]; d[2]=-y[2];
    return;
  }