Bisection And False Position Method C++


#include <bits/stdc++.h>
#include <iostream>
using namespace std;

double value(double A ,double B,double C,double x)
{
    return((A*x*x*x)+B*x+C);
}
int bisection(double A,double B,double C,double a,double b)
{
    int c=0;
    double xr1;
    double xr2=0.0;
    xr1=(a+b)/2.0;
    cout<<"n\ta\tb\txr\tf(x)\n"<<endl;
    do
    {
      c++;
      if(value(A,B,C,a)*(value(A,B,C,xr1))==0)
      {
          cout<<c<<"\t"<<a<<"\t"<<b<<"\t"<<xr1<<"\t"<<value(A,B,C,xr1)<<endl;
          break;
      }
      else if(value(A,B,C,a)*(value(A,B,C,xr1))<0)
      {
          cout<<c<<"\t"<<a<<"\t"<<b<<"\t"<<xr1<<"\t"<<value(A,B,C,xr1)<<endl;
          b=xr1;
          xr2=xr1;
          xr1=(a+b)/2.0;

      }
      else if(value(A,B,C,a)*(value(A,B,C,xr1))>0)
      {
          cout<<c<<"\t"<<a<<"\t"<<b<<"\t"<<xr1<<"\t"<<value(A,B,C,xr1)<<endl;
          a=xr1;
          xr2=xr1;
          xr1=(a+b)/2.0;


      }
    }while(fabs(xr1-xr2)>0.0001);
    cout<<"Root is="<<xr1<<endl;
    cout<<"Total Count="<<c<<endl;


}
int falseP(double A,double B,double C,double a,double b)
{
    int c=0;
    double xr1;
    xr1=(((a*(value(A,B,C,b)))-b*(value(A,B,C,a)))/(value(A,B,C,b)-value(A,B,C,a)));
    double xr2=0.0;
    cout<<"n\ta\tb\txr\tf(x)\n"<<endl;
    do
    {
        c++;
    if(value(A,B,C,a)*(value(A,B,C,xr1))==0)
      {
          cout<<c<<"\t"<<a<<"\t"<<b<<"\t"<<xr1<<"\t"<<value(A,B,C,xr1)<<endl;
          break;
      }
      else if(value(A,B,C,a)*(value(A,B,C,xr1))<0)
      {
          cout<<c<<"\t"<<a<<"\t"<<b<<"\t"<<xr1<<"\t"<<value(A,B,C,xr1)<<endl;
          b=xr1;
          xr2=xr1;
          xr1=(((a*(value(A,B,C,b)))-b*(value(A,B,C,a)))/(value(A,B,C,b)-value(A,B,C,a)));
      }
      else if(value(A,B,C,a)*(value(A,B,C,xr1))>0)
      {
          cout<<c<<"\t"<<a<<"\t"<<b<<"\t"<<xr1<<"\t"<<value(A,B,C,xr1)<<endl;
          a=xr1;
          xr2=xr1;
          xr1=(((a*(value(A,B,C,b)))-b*(value(A,B,C,a)))/(value(A,B,C,b)-value(A,B,C,a)));


      }
    }while(fabs(xr1-xr2)>0.0001);
    cout<<"Root is="<<xr1<<endl;
    cout<<"Total Count="<<c<<endl;

}

int main()
{
    double A,B,C;
    cout<<"Input Co-efficient of X^3 = ";
    cin>>A;
    cout<<"Input Co-efficient of X = ";
    cin>>B;
    cout<<"Input Constant = ";
    cin>>C;

    double a,b;
    for(a=0;a<1000;a++)
    {
        if(value(A,B,C,a)<0 && value(A,B,C,a+1)>0)
        {
           break;
        }
    }
    b=a+1;
    int s;
    cout<<"Enter your choice:\n1. For Bisection Method\n2.False Position Method"<<endl;
    while(cin>>s)
    {
        if(s==1)
        {
            bisection(A,B,C,a,b);
        }
        if(s==2)
        {
            falseP(A,B,C,a,b);
        }
        if(s==0)
        {
            break;
        }

    }

}

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About Ashadullah Shawon

I am Ashadullah Shawon. I am a Software Engineer. I studied Computer Science and Engineering (CSE) at RUET. I Like To Share Knowledge.
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