[求助]关于求解的算法 - 编程论坛

#2

HaPpY随心2007-10-15 12:34

#include <stdio.h>
#include <math.h>
float f(float x)
{
float y;
y=((2*x-4.0)*x+3)*x-6.0;
return y;
}

float xpiont(float x1,float x2)
{
float y;
y=(x1*f(x2)-x2*f(x1))/(f(x2)-f(x1));
return y;
}

float root (float x1,float x2)
{
float x,y,y1;
y1=f(x1);
do
{
x=xpiont(x1,x2);
y=f(x);
if(y*y1>0)
{
y1=y;
x1=x;
}
else
x2=x;
}while(fabs(y)>=0.0001);
return x;
}

void main()
{
float x1,x2,f1=1.0,f2=1.0,x;
while(f1*f2>=0)
{
printf("input x1,x2:\n");
fflush(stdin);
scanf("%f,%f",&x1,&x2);
f1=f(x1);
f2=f(x2);
}
x=root(x1,x2);
printf("A root of equation is %8.4f\n",x);
}

#3

HaPpY随心2007-11-05 16:18

上篇为2分法
这篇为牛顿迭代法

#include <cmath>
#include <iostream>
using namespace std;
void main()
{
double x=1,x0,f,f1;
do
{
x0=x;
f=((2.0*x0-3.0)*x0+4.0)*x0-6.0;
f1=(3*2.0*x0+2*(-3.0))*x0+4.0;
x=x0-f/f1;
}while(fabs(x-x0)>=1e-5);
cout <<"x="<<x<<endl;
}

#4

icelake2007-11-05 16:45

高手