C program for Bisection method

C program to implement bisection method in easy way..

bisection method theory

Here we have used a term tolerance value .Tolerance value is the difference between two consecutive

approximate roots of the equation that can be neglected.

As for example 1.00008 and 1.00004 are two approximate consecutive roots .

.One of them can be answer if there will be tolerance value of 0.00004 or greater otherwise not.

Here we have used a function fabs that returns the absolute double value and also takes double value 

as an argument.

 #include<conio.h>  
 #include<stdio.h>  
 #include<math.h>  
 float F(float x)  
 {  
   return x*x*x-x-1;  
 }  
 /*  
 f(0)=-ve  
 f(1)=-ve  here a=1 f(a)  
 f(2)=+ve  and b=2  
 tolerance value:0.0005  
 */  
 int main()  
 {  
   float a,b,c,d;  
   int i=0;  
   printf("Enter the interval(a,b) in which the roots of the equation lies::");  
   scanf("%f %f",&a,&b);  
   printf("\nEnter the tolerance value::");  
   scanf("%f",&d);  
   do{  
       c=(a+b)/2;  
       ++i;  
       if(F(a)*F(c)<0)//f(a)<0  
       {  b=c;  
         printf("\nValue of a and b in %d iteration is %f and %f",i,a,b);  
       }  
       else  
       {  
         a=c;  
         printf("\nValue of a and b in %d iteration is %f and %f",i,a,b);  
       }  
   }while(fabs(a-b)>d||F(c)==0);  
   printf("\nRoot is %f",c);  
   printf("\nPress any key to exit");  
   getche();  
   return 0;  
 }