Practical set 3 (False position)

#include<stdio.h>

#include<stdlib.h>

#include<math.h>

#define e 2.71828182

 

 

float fun(float x)

 {

    x=(x*x*x)-(2*x)-2;

//x=2*x-log10(x)-7;

//x=pow(x,3)-x-4;

//x=(x*(pow(e,x)))-2;

    return x;

 }

  

 float in(float a,float b)

 {

    float x;    x=((a*fun(b))-(b*fun(a)))/(fun(b)-fun(a));

    return x;

 }

  

 

  

 int main()

  {

      int i,n;

      float p[20];

      float a,b,x[100];

       

      printf("\n given question is : x^3+2x-2 =0 \n");

      printf("\n Enter n : ");scanf("%d",&n);

       

  for(i=0;i<n;i++)

   {

       p[i]=fun(i);

       printf("\n f[%d] : %0.1f ",i,p[i]);

   }

    

   for(i=0;i<n;i++)

    {

        if(p[i]*p[i+1]<0)

         {

            a=i;

            b=i+1;

            printf("\n\n your interval found between : [%2.4f %2.4f]",a,b);

            break;

            }      

        }

        for(i=0;i<n;i++)

        {

            x[i]=in(a,b);

            printf("\n x[%d] : %f " ,i,x[i]);

         

            if(fun(x[i])*fun(a) > 0)

            {

                a=x[i];

            }

            else

        {

            b=x[i];

        }

        }

     return 0;

 }

 

 

-----------------------------------------------------------------------------

another method

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

float f(float x) {
    float fx;
    fx = x*pow(2.714,x) -2;

//x=2*x-log10(x)-7;

//x=pow(x,3)-x-4;

//x=(x*(pow(e,x)))-2;

    return fx;
}

float rootB(float a, float b) {
    float c;
    c = (((a*f(b))-(b*f(a))))/(f(b)-f(a));
    if(f(c)==0){
        printf("%f ",f(c));
        return c;
    }
    else if(f(c)<0) {
        return rootB(c,b);
    }
    else{
        return rootB(a,c);
    }
}


int main()
{
   float a,b,ans;
   float i;
   for(i=-5;i<=5;i++) {
        if(f(i)*f(i+1)<0) {
            if(f(i)<0){
                ans  = rootB(i,i+1);
            }
            else {
                ans = rootB(i+1,i);
            }
            printf("ans is %f",ans);
        }
    }




    return 0;

}



By - Sahil Patki