Changeset 9578 for trunk/MagicSoft/Mars/mastro

Timestamp:

05/05/10 09:51:51 (15 years ago)

Author:

tbretz

Message:

*** empty log message ***

File:

• trunk/MagicSoft/Mars/mastro/MAstro.cc (modified) (1 diff)

trunk/MagicSoft/Mars/mastro/MAstro.cc

@@ -376 +376 @@
 Double_t MAstro::AngularDistance(Double_t theta0, Double_t phi0, Double_t theta1, Double_t phi1)
 {
-    TVector3 v0(1);
-    v0.Rotate(phi0, theta0);
-
-    TVector3 v1(1);
-    v1.Rotate(phi1, theta1);
-
-    return v0.Angle(v1);
+    // v1 = theta0/phi0 --> theta0 / 0
+    // v2 = theta1/phi1 --> theta1 / phi1-phi0
+    // acos(alpha) = v1*v2/|v1||v2|    |v1|*|v2|=1
+    const Double_t sin2 = TMath::Sin(theta0)*TMath::Sin(theta1);
+    const Double_t cos2 = TMath::Cos(theta0)*TMath::Cos(theta1);
+
+    return TMath::ACos(sin2*TMath::Cos(phi1-phi0) + cos2);
+    /*
+     TVector3 v0;
+     v0.SetMagThetaPhi(1, theta0, phi0);
+
+     TVector3 v1;
+     v1.SetMagThetaPhi(1, theta0, phi0);
+
+     return v0.Angle(v1);
+     */
 }