diff options
Diffstat (limited to 'libtellurian_effective_gravity_radians.c')
-rw-r--r-- | libtellurian_effective_gravity_radians.c | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/libtellurian_effective_gravity_radians.c b/libtellurian_effective_gravity_radians.c new file mode 100644 index 0000000..54e2b8e --- /dev/null +++ b/libtellurian_effective_gravity_radians.c @@ -0,0 +1,51 @@ +/* See LICENSE file for copyright and license details. */ +#include "common.h" + +#define K (LIBTELLURIAN_EQUATORIAL_RADIUS * LIBTELLURIAN_ANGULAR_VELOCITY * LIBTELLURIAN_ANGULAR_VELOCITY) + +#ifndef TEST + + +double +libtellurian_effective_gravity_radians(double gravity, double latitude) +{ + return fma(-K / gravity, cos(latitude) * cos(latitude), gravity); +} + + +#else + + +static int +approx(double a, double b) +{ + return fabs(a - b) <= 1e-8 * (0.5 * (a + b)); +} + +int +main(void) +{ + ASSERT(libtellurian_effective_gravity_radians(1, D90) == 1); + ASSERT(libtellurian_effective_gravity_radians(2, D90) == 2); + ASSERT(libtellurian_effective_gravity_radians(4, D90) == 4); + ASSERT(libtellurian_effective_gravity_radians(1, -D90) == 1); + ASSERT(libtellurian_effective_gravity_radians(2, -D90) == 2); + ASSERT(libtellurian_effective_gravity_radians(4, -D90) == 4); + ASSERT(libtellurian_effective_gravity_radians(1, 0) == fma(1.00, -K, 1.0)); + ASSERT(libtellurian_effective_gravity_radians(2, 0) == fma(0.50, -K, 2.0)); + ASSERT(libtellurian_effective_gravity_radians(4, 0) == fma(0.25, -K, 4.0)); + ASSERT(libtellurian_effective_gravity_radians(1, D45) == fma(0.50, -K, 1.0)); + ASSERT(libtellurian_effective_gravity_radians(2, D45) == fma(0.25, -K, 2.0)); + ASSERT(libtellurian_effective_gravity_radians(1, D60) == fma(0.250, -K, 1.0)); + ASSERT(libtellurian_effective_gravity_radians(2, D60) == fma(0.125, -K, 2.0)); + ASSERT(libtellurian_effective_gravity_radians(4, D30) < 4); + ASSERT(libtellurian_effective_gravity_radians(4, D30) > libtellurian_effective_gravity_radians(4, 0)); + ASSERT(approx(libtellurian_effective_gravity_radians(LIBTELLURIAN_NORMAL_POLAR_GRAVITY, D90), + LIBTELLURIAN_POLAR_GRAVITY)); + ASSERT(approx(libtellurian_effective_gravity_radians(LIBTELLURIAN_NORMAL_EQUATORIAL_GRAVITY, 0), + LIBTELLURIAN_EQUATORIAL_GRAVITY)); + return 0; +} + + +#endif |