spir0.c

最小二乘法——一般多项式拟合曲线

  #include "stdio.h"
  #include "spir.c"
  #include "math.h"
  main()
  { int i;
    double x[20],y[20],a[7],dt[3];
    for (i=0; i<=19; i++)
      { x[i]=0.1*i;
        y[i]=x[i]-exp(-x[i]);
      }
    spir(x,y,20,a,7,dt);
    printf("\n");
    for (i=0; i<=6; i++)
      printf("a(%2d)=%e\n",i,a[i]);
    printf("\n");
    for (i=0; i<=2; i++)
      printf("dt(%2d)=%e  ",i,dt[i]);
    printf("\n\n");
  }