1 files changed, 14 insertions, 0 deletions
diff --git a/libtellurian_transverse_radius_radians.c b/libtellurian_transverse_radius_radians.c
new file mode 100644
index 0000000..dae8f04
--- /dev/null
+++ b/libtellurian_transverse_radius_radians.c
@@ -0,0 +1,14 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+double
+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 s = sin(latitude);
+	return pow(fma(neg_e2, s * s, 1.0), -0.5);
+}