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/* See LICENSE file for copyright and license details. */
#include "common.h"
#ifndef TEST
double
libtellurian_normal_gravity_radians(double latitude)
{
double a = LIBTELLURIAN_EQUATORIAL_RADIUS;
double b = LIBTELLURIAN_POLAR_RADIUS;
double neg_e2 = fma(b / a, b / a, -1.0);
double ag = a * LIBTELLURIAN_NORMAL_EQUATORIAL_GRAVITY;
double bg = b * LIBTELLURIAN_NORMAL_POLAR_GRAVITY;
double k = bg / ag - 1.0;
double sin2_phi = sin(latitude) * sin(latitude);
double num = fma(k, sin2_phi, 1.0);
double denom2 = fma(neg_e2, sin2_phi, 1.0);
return LIBTELLURIAN_NORMAL_EQUATORIAL_GRAVITY * num / sqrt(denom2);
}
#else
static int
approx(double a, double b)
{
return fabs(a / b - 1.0) <= 1e-12;
}
int
main(void)
{
ASSERT(approx(libtellurian_normal_gravity_radians(D30), libtellurian_normal_gravity_radians(-D30)));
ASSERT(approx(libtellurian_normal_gravity_radians(D45), libtellurian_normal_gravity_radians(-D45)));
ASSERT(approx(libtellurian_normal_gravity_radians(D60), libtellurian_normal_gravity_radians(-D60)));
ASSERT(approx(libtellurian_normal_gravity_radians(D90), libtellurian_normal_gravity_radians(-D90)));
ASSERT(approx(libtellurian_normal_gravity_radians(D180), libtellurian_normal_gravity_radians(0)));
ASSERT(approx(libtellurian_normal_gravity_radians(-D180), libtellurian_normal_gravity_radians(0)));
ASSERT(approx(libtellurian_normal_gravity_radians(2.0), libtellurian_normal_gravity_radians(-2.0)));
ASSERT(approx(libtellurian_normal_gravity_radians(0), LIBTELLURIAN_NORMAL_EQUATORIAL_GRAVITY));
ASSERT(approx(libtellurian_normal_gravity_radians(D90), LIBTELLURIAN_NORMAL_POLAR_GRAVITY));
ASSERT(libtellurian_normal_gravity_radians(D45) < LIBTELLURIAN_NORMAL_POLAR_GRAVITY);
ASSERT(libtellurian_normal_gravity_radians(D45) > LIBTELLURIAN_NORMAL_EQUATORIAL_GRAVITY);
return 0;
}
#endif
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