#include <stdio.h>
#include <math.h>
int main()
{
    float actual_val, approx_val, actual_err, relative_err, percentage_err;
    printf("Enter Actual value : ");
    scanf("%f", &actual_val);
    printf("Enter Approx value : ");
    scanf("%f", &approx_val);
    actual_err = fabs(actual_val - approx_val);
    relative_err = actual_err / actual_val;
    percentage_err = relative_err * 100;
    printf("\nActual Error = %f", actual_err);
    printf("\nRelative Error = %f", relative_err);
    printf("\nPercentage Error = %f%%\n", percentage_err);
    return 0;
}
                        
                
                        
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define EPSILON 0.003
float f(float x)
{
    return x * x * x - 9 * x + 1;
}
int main()
{
    float xmid, x1, x2;
    int i = 1;
    printf("Enter the initial guess : ");
    scanf("%f%f", &x1, &x2);
    if (f(x1) * f(x2) > 0)
    {
        printf("Wrong Assumptions");
        exit(0);
    }
    do
    {
        xmid = (x1 + x2) / 2;
        if (f(xmid) * f(x1) < 0)
            x2 = xmid;
        else
            x1 = xmid;
        printf("Root after %d iteration is = %f\n", i, xmid);
        i++;
    } while (fabs(f(xmid)) > EPSILON);
    return 0;
}
                        
                
                        
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#define EPSILON 0.003
float f(float x)
{
    return x * x * x - 9 * x + 1;
}

int main()
{
    float x1, x2, xn;
    int i = 1;
    printf("Enter Initial Guess: ");
    scanf("%f", &x1);
    scanf("%f", &x2);

    if (f(x1) * f(x2) > 0)
    {
        printf("\nAssumptions are wrong!");
        exit(0);
    }
    do
    {
        xn = ((x1 * f(x2)) - (x2 * f(x1))) / (f(x2) - f(x1));
        if (f(xn) * f(x1) < 0)
            x2 = xn;
        else
            x1 = xn;
        printf("\nRoot after %d iteration = %f\n", i, xn);
        i++;
    } while (fabs(f(xn)) > EPSILON);
    return 0;
}
                        
                
                        
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define EPSILON 0.003
float f(float x)
{
    return x * x * x - 4 * x - 9;
}
float fx2(float x0, float x1)
{
    return x0 - (((x1 - x0) / (f(x1) - f(x0))) * f(x0));
}

int main()
{
    float x0, x1, x2;
    int i = 1;
    printf("Enter Initial Guess: ");
    scanf("%f%f", &x0, &x1);
    if (f(x0) * f(x1) > 0) {
        printf("Assumptions are wrong! The guesses do not bracket a root.\n");
        exit(0);
    }
    do
    {
        x2 = ((x0 * f(x1)) - (x1 * f(x0))) / (f(x1) - f(x0));
        x0 = x1;
        x1 = x2;
        printf("Root after iteration = %d is %f and value of function = %f\n", i, x2, f(x2));
        i++;
    } while (fabs(f(x2)) > EPSILON);
    return 0;
}
                        
                
                        
#include <stdio.h>
#include <math.h>
#define EPSILON 0.003

float f(float x)
{
    return ((x * x * x) - 4 * x - 9);
}
float df(float x)
{
    return (3 * x * x - 4);
}

int main()
{
    float x0, x1;
    int i = 1;
    printf("Enter intial guess: ");
    scanf("%f", &x0);
    do
    {
        x1 = x0 - (f(x0) / df(x0));
        x0 = x1;
        printf("No. of iteration = %d\t Root = %f\t Value of function = %f\n", i, x1, f(x1));
        i++;
    } while (fabs(f(x1)) > EPSILON);
    return 0;
}
                        
                
                        
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#define e 0.003

float f(float x)
{
    return x * x * x - 9 * x + 1;
}

float g1(float x)
{
    return pow((9 * x - 1), 1 / 3);
}

float g2(float x)
{
    return ((1 + x * x * x) / 9);
}

int main()
{
    int i = 0;
    float a, b, xm, diff;
    int ch;
    printf("Enter two initial guess = ");
    scanf("%f%f", &a, &b);
    if (f(a) * f(b) > 0)
    {
        printf("You assumptions were wrong");
        exit(0);
    }
    xm = (a + b) / 2;
    printf("Enter your choice for choice between two method (1 & 2) : ");
    scanf("%d", &ch);
    if (ch == 1)
    {
        do
        {
            float xnew = g1(xm);
            diff = fabs(xnew - xm);
            xm = xnew;
            i++;
            printf("No. of iteration = %d", i);
            printf("Your root is : %f", xnew);
        } while (fabs(diff) > e);
    }
    else if (ch == 2)
    {
        do
        {
            float xnew = g2(xm);
            float diff = fabs(xnew - xm);
            xm = xnew;
            printf("No. of iteration : %d", i);
            printf("Your root is : %f", xnew);
        } while (fabs(diff > e));
    }
    else
    {
        printf("Either choose 1 or 2");
        exit(0);
    }
    return 0;
}
                        
                
                        
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define EPSILON 0.003

float f(float x)
{
    return x * x * x - 9 * x + 1;
}

float df(float x)
{
    return 3 * x * x - 9;
}
int i1 = 1, i2 = 1;
float bisectionMethod(float x1, float x2)
{
    float xmid;
    do
    {
        xmid = (x1 + x2) / 2;
        if ((f(xmid) * f(x1)) < 0)
        {
            x2 = xmid;
        }
        else
        {
            x1 = xmid;
        }
        i1++;
    } while (fabs(f(xmid)) > EPSILON);
    return xmid;
}
float newtonMethod(float x0)
{
    float f0, x1, f1, dx0;
    do
    {
        f0 = f(x0);
        dx0 = df(x0);
        x1 = x0 - (f0 / dx0);
        f1 = f(x1);
        x0 = x1;
        i2++;
    } while (fabs(f1) > EPSILON);
    return x1;
}
int main()
{
    float b1, b2, n0;
    printf("Enter initial Guess for Bisection method : ");
    scanf("%f%f", &b1, &b2);
    printf("Enter initial Guess for Newton Ralphson method : ");
    scanf("%f", &n0);
    printf("It took %d iteration in Bisection method and the value of root is = %f\n", i1, bisectionMethod(b1, b2));
    printf("It took %d iteration in Newton Ralphson method and the value of root is = %f\n", i2, newtonMethod(n0));

    return 0;
}
                        
                
                        
#include <stdio.h>
void main()
{
    int n, i, j, k;
    float a[10][10], u;
    printf("\n Enter number of unknowns:");
    scanf("%d", &n);
    printf("Enter coefficients:");
    for (i = 0; i < n; i++)
        for (j = 0; j < n + 1; j++)
            scanf("%f", &a[i][j]);
    printf("\n Entered Matrix:\n");
    for (i = 0; i < n; i++)
    {
        for (j = 0; j < n + 1; j++)
        {
            printf("\t%f", a[i][j]);
        }
        printf("\n");
    }

    // Transformation
    for (i = 0; i < n - 1; i++)
        for (j = i + 1; j < n; j++)
        {
            u = a[j][i] / a[i][i];
            for (k = 0; k < n + 1; k++)
                a[j][k] = a[j][k] - u * a[i][k];
        }

    printf("\nUper Triangular Matrix Elements:\n");
    for (i = 0; i < n; i++)
    {
        for (j = 0; j < n + 1; j++)
            printf("%f\t", a[i][j]);
        printf("\n");
    }
}
                        
                
                        
#include <stdio.h>

int main()
{
    int i, j, k, n;
    float a[10][10], x[10], u, sum;

    printf("\nEnter number of unknowns: ");
    scanf("%d", &n);

    printf("\nEnter [A:B] matrix:\n");
    for (i = 0; i < n; i++)
    {
        for (j = 0; j < n + 1; j++)
        {
            scanf("%f", &a[i][j]);
        }
    }

    // Transform to upper triangular matrix
    for (i = 0; i < n - 1; i++)
    {
        for (j = i + 1; j < n; j++)
        {
            u = a[j][i] / a[i][i];
            for (k = 0; k < n + 1; k++)
            {
                a[j][k] = a[j][k] - u * a[i][k];
            }
        }
    }

    printf("\nUpper Triangular Matrix Elements:\n");
    for (i = 0; i < n; i++)
    {
        for (j = 0; j < n + 1; j++)
        {
            printf("%f\t", a[i][j]);
        }
        printf("\n");
    }

    // Back substitution
    for (i = n - 1; i >= 0; i--)
    {
        sum = 0;
        for (j = i + 1; j < n; j++)
        {
            sum += a[i][j] * x[j]; /* Performing Back Substitution */
        }
        x[i] = (a[i][n] - sum) / a[i][i];
    }

    printf("\nSolution values are:\n");
    for (i = 0; i < n; i++)
    {
        printf("%f\n", x[i]);
    }

    return 0;
}
                        
                    
                        
#include <stdio.h>

float findValueAt(float x)
{
    return x * x * x;
}

int main()
{
    int n;
    float sum = 0, h, a, b, i;
    printf("Enter the upper limit value : ");
    scanf("%f", &a);
    printf("Enter the lower limit value : ");
    scanf("%f", &b);
    printf("Enter the number of Intervals : ");
    scanf("%d", &n);
    sum = findValueAt(a) + findValueAt(b);
    h = (a + b) / n;
    for (i = a + h; i < b; i = i + h)
    {
        sum = sum + (2 * findValueAt(i));
    }
    sum = (sum * h) / 2;
    printf("Value of the Integral is = %f\n", sum);
    return 0;
}
                        
                

Reference: