Thread: Help C programming that reads value of x and n?

C program that reads the value of x and n from the keyboard and then approximately computes the value of cos(x) using the following formula:

Cosx = 1 - x^2/2! + x^4/4! - x^6/6! .....+ (-1)^n x^2n/(2n)!

(Written)
cos of x equal 1 minus x square over two ! plus x to the fourth over 4! minus x to the sixth over six !.......plus(minus one) to the n...
x squared n over (two n) !

Can you all check if the middle part of the code is correct.

Code:

#include <stdio.h>
#include <math.h>
int main (void)
{

/*Declare variables*/
int i, n;
double x, cos;

printf("Enter the value of x and n: ");
scanf("%lf %d", &x, &n);


/* loop to compute cosx using above formula*/ 

/*Please can  you all check this part"*/

double cos=1;
int count=2;
int p=1;
int fact=1;
int i,j;

for( i = 0; i <= n; i=i+2)
{
if (i!=0)
{
//for x^2, x^4, x^6....
for(j=1;j<=i;j++)
p=p*x;

//for factorial
for(j=1;j<=i;j++)
fact=fact*j;

if(count%2==0)
cos -= p/fact;
else
cos += p/fact;
}
count++;
}













printf("Approximate cosx is %lf when n=%d \n", cosx, n);
printf("Cos(x) in math lib returns %lf \n", Cos(x));


system ("pause")

return 0;

}

It would be simpler for you to use print statements for each iteration of factorial and for the values of x^n to determine if the loops are equating the correct values or you!

I indented the code hope it helps.

Code:

#
#include <stdio.h>
#
#include <math.h>
#
int main(void)
#
{
#
 
#
/*Declare variables*/
#
int i, n;
#
double x, cos;
#
 
#
printf("Enter the value of x and n: ");
#
scanf("%lf %d", &x, &n);
#
 
#
 
#
/* loop to compute cosx using above formula*/
#
 
#
/*Please can you all check this part"*/
#
 
#
double cos = 1;
#
int count = 2;
#
int p = 1;
#
int fact = 1;
#
int i, j;
#
 
#
for (i = 0; i <= n; i = i + 2) {
#
if (i != 0) {
#
//for x^2, x^4, x^6....
#
for (j = 1; j <= i; j++)
#
p = p * x;
#
 
#
//for factorial
#
for (j = 1; j <= i; j++)
#
fact = fact * j;
#
 
#
if (count % 2 == 0)
#
cos -= p / fact;
#
else
#
cos += p / fact;
#
}
#
count++;
#
}
#
 
#
 
#
 
#
 
#
 
#
 
#
 
#
 
#
 
#
 
#
 
#
 
#
 
#
printf("Approximate cosx is %lf when n=%d \n", cosx, n);
#
printf("Cos(x) in math lib returns %lf \n", Cos(x));
#
 
#
 
#
system("pause")
#
 
#
return 0;
#
 
#
}