C Language Standard Math Power functions - pow(), powf(), powl()
Example
The following example code computes the sum of 1+4(3+3^2+3^3+3^4+...+3^N) series using pow() family of standard math library.
#include <stdio.h>
#include <math.h>
#include <errno.h>
#include <fenv.h>
int main()
{
double pwr, sum=0;
int i, n;
printf("\n1+4(3+3^2+3^3+3^4+...+3^N)=?\nEnter N:");
scanf("%d",&n);
if (n<=0) {
printf("Invalid power N=%d", n);
return -1;
}
for (i=0; i<n+1; i++) {
errno = 0;
feclearexcept(FE_ALL_EXCEPT);
pwr = powl(3,i);
if (fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
FE_UNDERFLOW)) {
perror("Math Error");
}
sum += i ? pwr : 0;
printf("N= %d\tS= %g\n", i, 1+4*sum);
}
return 0;
}
Example Output:
1+4(3+3^2+3^3+3^4+...+3^N)=?
Enter N:10
N= 0 S= 1
N= 1 S= 13
N= 2 S= 49
N= 3 S= 157
N= 4 S= 481
N= 5 S= 1453
N= 6 S= 4369
N= 7 S= 13117
N= 8 S= 39361
N= 9 S= 118093
N= 10 S= 354289
