| pe_loxodrome_distance | |
Finds the distance and forward and inverse azimuths between two points along a loxodrome
void pe_loxodrome_distance (double a, double e2, double lam1, double phi1, double lam2, double phi2, double *distance, double *az12, double *az21);
| a | Semimajor axis of the spheroid |
| e2 | Eccentricity squared of the spheroid |
| lam1 | Longitude value of the first point |
| phi1 | Latitude value of the first point |
| lam2 | Longitude value of the second point |
| phi2 | Latitude value of the second point |
| distance | Distance |
| az12 | Azimuth from the first to the second point |
| az21 | Azimuth from the second to the first point |
The pe_loxodrome_distance function takes a spheroid and two geographic points and calculates the distance and azimuths along the loxodrome. A loxodrome, or rhumb line, is the path of equal bearing between two points on a spheroid. The Mercator projection has the special property that straight lines are loxodromes. This property makes the Mercator projection useful when navigating a course. Set e2 to zero to calculate distance on a sphere. The geographic coordinates and the azimuths are in radians. The azimuth value range is -π ≤ azimuth ≤ +π. An azimuth is measured positive clockwise with North equal to a zero azimuth. The semimajor axis (a) is usually given in meters, which means that the distance is in meters. To return the distance in another linear unit of measure, specify the semimajor axis in that unit of measure. As an example, if the semimajor axis is in US survey feet, the returned distance is in US survey feet.
Distance and forward and inverse azimuths (in radians)