发信人: chdw()
整理人: jinhu(1999-06-30 20:26:25), 站内信件
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【 在 boho (boho) 的大作中提到: 】
: 用牛顿迭代法，求方程2x^3-4x^2+3x-6=0在1.5附近的根。谢谢！
#include <stdio.h>
#include "math.h"
#define fadhrtf(x) .....
#define A 1.0
#define B 1.5
#define EPS .0001
void fadhrt(a,b,h,eps,x,m)
int m[2];
double a,b,h,eps,x[];
{ int n,js;
double z,y,z1,y1,z0,y0;
n=0; z=a; y=fadhrtf(z);
while ((z<=b+h/2.0)&&(n!=m[0]))
{ if (fabs(y)<eps)
{ n=n+1; x[n-1]=z;
z=z+h/2.0; y=fadhrtf(z);
}
else
{ z1=z+h; y1=fadhrtf(z1);
if (fabs(y1)<eps)
{ n=n+1; x[n-1]=z1;
z=z1+h/2.0; y=fadhrtf(z);
}
else if (y*y1>0.0)
{ y=y1; z=z1;}
else
{ js=0;
while (js==0)
{ if (fabs(z1-z)<eps)
{ n=n+1; x[n-1]=(z1+z)/2.0;
z=z1+h/2.0; y=fadhrtf(z);
js=1;
}
else
{ z0=(z1+z)/2.0; y0=fadhrtf(z0);
if (fabs(y0)<eps)
{ x[n]=z0; n=n+1; js=1;
z=z0+h/2.0; y=fadhrtf(z);
}
else if ((y*y0)<0.0)
{ z1=z0; y1=y0;}
else { z=z0; y=y0;}
}
}
}
}
}
m[1]=n;
return;
}
main()
{ int i;
static int m[2]={6,0};
static double x[6];
fadhrt(A,B,(B-A)/2,EPS,x,m);
printf("M=%d\n",m[1]);
for (i=0; i<=m[1]-1; i++)
printf("x(%d)=%lf\n",i,x[i]);
printf("\n");
}
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