regula falsi c program
/* Program: Finding real roots of nonlinear
equation using Regula Falsi or False Position Method
Author: CodeSansar
Date: November 18, 2018 */
/* Header Files */
#include<stdio.h>
#include<conio.h>
#include<math.h>
/* Defining equation to be solved.
Change this equation to solve another problem. */
#define f(x) x*log10(x) - 1.2
int main()
{
float x0, x1, x2, f0, f1, f2, e;
int step = 1;
clrscr();
/* Inputs */
up:
printf("\nEnter two initial guesses:\n");
scanf("%f%f", &x0, &x1);
printf("Enter tolerable error:\n");
scanf("%f", &e);
/* Calculating Functional Values */
f0 = f(x0);
f1 = f(x1);
/* Checking whether given guesses brackets the root or not. */
if( f0*f1 > 0.0)
{
printf("Incorrect Initial Guesses.\n");
goto up;
}
/* Implementing Regula Falsi or False Position Method */
printf("\nStep\t\tx0\t\tx1\t\tx2\t\tf(x2)\n");
do
{
x2 = x0 - (x0-x1) * f0/(f0-f1);
f2 = f(x2);
printf("%d\t\t%f\t%f\t%f\t%f\n",step, x0, x1, x2, f2);
if(f0*f2 < 0)
{
x1 = x2;
f1 = f2;
}
else
{
x0 = x2;
f0 = f2;
}
step = step + 1;
}while(fabs(f2)>e);
printf("\nRoot is: %f", x2);
getch();
return 0;
}