From 09e6857ae73249bc7433f2971dcf291c70e4c766 Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Sun, 20 Oct 2024 17:28:46 +0200 Subject: Fourth commit MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- libtellurian_transverse_radius_radians.c | 34 +++++++++++++++++++++++++++++--- 1 file changed, 31 insertions(+), 3 deletions(-) (limited to 'libtellurian_transverse_radius_radians.c') diff --git a/libtellurian_transverse_radius_radians.c b/libtellurian_transverse_radius_radians.c index dae8f04..c4f80aa 100644 --- a/libtellurian_transverse_radius_radians.c +++ b/libtellurian_transverse_radius_radians.c @@ -1,5 +1,6 @@ /* See LICENSE file for copyright and license details. */ #include "common.h" +#ifndef TEST double @@ -7,8 +8,35 @@ libtellurian_transverse_radius_radians(double latitude) { double a = LIBTELLURIAN_EQUATORIAL_RADIUS; double b = LIBTELLURIAN_POLAR_RADIUS; - double f = 1.0 - b / a; - double neg_e2 = (f - 2.0) * f; + double neg_e2 = fma(b / a, b / a, -1.0); double s = sin(latitude); - return pow(fma(neg_e2, s * s, 1.0), -0.5); + return a * pow(fma(neg_e2, s * s, 1.0), -0.5); } + + +#else + + +static int +approx(double a, double b) +{ + return fabs(a - b) <= 1e-8 * (0.5 * (a + b)); +} + +int +main(void) +{ + ASSERT(libtellurian_transverse_radius_radians(0) == LIBTELLURIAN_EQUATORIAL_RADIUS); + ASSERT(approx(libtellurian_transverse_radius_radians(D180), LIBTELLURIAN_EQUATORIAL_RADIUS)); + ASSERT(approx(libtellurian_transverse_radius_radians(-D180), LIBTELLURIAN_EQUATORIAL_RADIUS)); + ASSERT(approx(libtellurian_transverse_radius_radians(D30), libtellurian_transverse_radius_radians(-D30))); + ASSERT(approx(libtellurian_transverse_radius_radians(D45), libtellurian_transverse_radius_radians(-D45))); + ASSERT(approx(libtellurian_transverse_radius_radians(D60), libtellurian_transverse_radius_radians(-D60))); + ASSERT(approx(libtellurian_transverse_radius_radians(D90), libtellurian_transverse_radius_radians(-D90))); + ASSERT(fabs(libtellurian_transverse_radius_radians(D90) - 6399593.625758674) / 6399593.625758674 < 1.0e-8); + ASSERT(fabs(libtellurian_transverse_radius_radians(D30) - 6383480.917690154) / 6383480.917690154 < 1.0e-8); + return 0; +} + + +#endif -- cgit v1.2.3-70-g09d2