dichotomy.c

我自己写的数值分析课程设计的源代码

#include<stdio.h>
#include<math.h>

#define  TOL    1E-11
#define  NO     50

double f(double x)
{
	return 3*x+sin(x)-exp(x);
}

void main()
{
	FILE *file;
	double x_1 = 0;
	double x_2 = 1;
	double y_1 = f(x_1);
	double y_2 = f(x_2);
	double x = 0;
	int i = 2;
	file=fopen("logo.txt","a+");
	while(i<NO)
	{		
		x = (x_1+x_2)/2;

		if(fabs(f(x))<TOL)
		{
			fprintf(file,"根为 x = %.15Lg\n",x);
			
		}
		if(f(x)*y_1<0)
		{
			x_2 = x;
			y_2 = f(x_2);
		}
		else if(f(x)*y_2<0)
		{
			x_1 = x;
			y_1 = f(x_1);
		}
		i++;
	}
	fprintf(file,"method failed after %d iterations.\n",NO);
	
}