Catenary Equation in C

catenary.c

#include <stdio.h>
#include <math.h>

double catenary(const double x, const double a) {
  return a * cosh(x / a);
}

double catenary_with_eulers(const double x, const double a) {
  return (a / 2.0) * (exp(x / a) + exp(-x / a));
}

int main(void) {
  const double x = -2.0;
  const double a = 2.0;
  const double y1 = catenary(x, a);
  const double y2 = catenary_with_eulers(x, a);
  printf("Hyperbolic cosine of %lf (in radians) = %lf\n", x, y1);
  printf("Hyperbolic cosine of %lf (in radians) = %lf\n", x, y2);
}