C Program to Calculate the Sum of cos(x) Series


This is a C Program to calculate the sum of cos(x) series.

Problem Description

This C Program calculates the sum of cos(x) series.

Problem Solution

Take input from the user and perform operations as shown in the program below.

Program/Source Code

Here is source code of the C program to C Program calculates the sum of cos(x) series. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

 * C program to find the sum of cos(x) series
#include <stdio.h>
#include <math.h>
void main()
    int n, x1, i, j;
    float x, sign, cosx, fact;
    printf("Enter the number of the terms in a series\n");
    scanf("%d", &n);
    printf("Enter the value of x(in degrees)\n");
    scanf("%f", &x);
    x1 = x;
	/*  Degrees to radians */
    x = x * (3.142 / 180.0);
    cosx = 1;
    sign = -1;
    for (i = 2; i <= n; i = i + 2)
        fact = 1;
        for (j = 1; j <= i; j++)
            fact = fact * j;
        cosx = cosx + (pow(x, i) / fact) * sign;
        sign = sign * (-1);
    printf("Sum of the cosine series = %7.2f\n", cosx);
    printf("The value of cos(%d) using library function = %f\n", x1,
Program Explanation

In this C program, library function defined in <math.h> header file is used to compute mathematical functions. We are reading the number of the terms and the degree value of the series using ‘n’ and ‘x’ variables. To find the sum of cos(x) series, the following formula is used.
Cos(x) = cosx + (pow (x, i) / fact) * sign

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Runtime Test Cases
$ cc pgm63.c -lm
$ a.out
Enter the number of the terms in a series
Enter the value of x(in degrees)
Sum of the cosine series =   -0.23
The value of cos(90) using library function = -0.000204

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If you wish to look at other example programs on Mathematical Functions, go to C Programming Examples on Mathematical Functions. If you wish to look at programming examples on all topics, go to C Programming Examples.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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