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authorJohannes Hofmann <Johannes.Hofmann@gmx.de>2008-05-28 19:18:53 +0200
committerJohannes Hofmann <Johannes.Hofmann@gmx.de>2008-05-28 19:18:53 +0200
commit2dfdc09969b8c32887cb45b6f7ff286227ddfd27 (patch)
tree6203b051ce472fb9c740934bd63ab38a4af4d8e7
parent090788ca04d1620c258d3a1e9053b907e87ec3c1 (diff)
use numerical more stable distance formula
-rw-r--r--src/Panorama.cxx8
1 files changed, 5 insertions, 3 deletions
diff --git a/src/Panorama.cxx b/src/Panorama.cxx
index 32e14f4..8bab3e4 100644
--- a/src/Panorama.cxx
+++ b/src/Panorama.cxx
@@ -413,8 +413,11 @@ Panorama::update_coordinates() {
double
Panorama::distance(double phi, double lam) {
- return acos(sin(view_phi) * sin(phi) +
- cos(view_phi) * cos(phi) * cos(view_lam - lam));
+ double d_lam = view_lam - lam;
+
+ return atan2(sqrt(pow(cos(phi) * sin(d_lam), 2.0) +
+ pow(cos(view_phi) * sin(phi) - sin(view_phi) * cos(phi) * cos(d_lam), 2.0)),
+ sin(view_phi) * sin(phi) + cos(view_phi) * cos(phi) * cos(d_lam));
}
double
@@ -428,7 +431,6 @@ Panorama::alpha(const Hill *m) {
return fmod(atan2(sin_alph, cos_alph) + 2.0 * pi_d, 2.0 * pi_d);
}
-
double
Panorama::nick(const Hill *m) {
double b, c;