Statistical and Numerical Techniques || C codes

Bisection Method

#include<stdio.h>
#include<math.h>
float fun (float x)
{
    return (x*x*x - 4*x + 9);
}
void bisection (float *x, float a, float b, int *itr)
 /* this function performs and prints the result of  one iteration */     
{
*x=(a+b)/2;
++(*itr);
printf("Iteration no. %3d X = %7.5f\n", *itr, *x);
}
int main ()
{
int itr = 0, maxmitr;
float x, a, b, allerr, x1;
printf("\nEnter the values of a, b, allowed error and maximum iterations:\n");
scanf("%f %f %f %d", &a, &b, &allerr, &maxmitr);
bisection (&x, a, b, &itr);
do
{
     if (fun(a)*fun(x) < 0)
     b=x;
     else
      a=x;
     bisection (&x1, a, b, &itr);
      if (fabs(x1-x) < allerr)
      {
        printf("After %d iterations, root = %6.4f\n", itr, x1);
        return 0;
       }
       x=x1;
 }
 while (itr < maxmitr);
 printf("The solution does not converge or iterations are not sufficient");
}

OUTPUT:

Bisection Method

Lagrange Interpolation

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

void main()
{
        float x[6], y[6],sum=0,temp,a;
        int i,j;
        printf("Enter the values for x:");
        for(i=0;i<4;i++)
          scanf("%f",&x[i]);
        printf("Enter y:");
        for(i=0;i<4;i++)
          scanf("%f",&y[i]);
        printf("Enter point:");
        scanf("%f",&a);
        for(i=0;i<4;i++)
         {
           temp=1.0;
           for(j=0;j<4;j++)
             {
                if(i!=j)
                temp=temp*((a-x[j])/(x[i]-x[j]));
             }
           sum=sum+temp*y[i];
         }
    printf("Solution: %f",sum);

}

OUTPUT:

Interpolation

Regula Falsi Method

#include<stdio.h>
#include<math.h>
float f(float x)
{
   return ((x*exp(x))-2);
}

void main()
{

  int i;
  float a,b,x;
 printf("Enter value of a: ");
 scanf("%f",&a);
  printf("Enter the value of b: ");
  scanf("%f",&b);
for(i=0;i<=20;i++)
{

x=(((a*f(b))-(b*f(a)))/(f(b)-f(a)));
if(f(a)*f(x)<0)
 b=x;
else
a=x;
printf("Root at %d iteration is %f\n",i,x);
}

}

OUTPUT:

Regula-Falsi method

NOTE:
The Above Code in Bold Letters May Change according to the Question (You can Edit it on your Own).