Changeset 54de04 for molecuilder

Timestamp:

Jul 7, 2009, 8:12:28 AM (16 years ago)

Author:

Frederik Heber <heber@…>

Children:

d98327

Parents:

eeae5b

Message:

BUGFIX: Numerical imprecision forced check of bounds for acos()

Scalarproduct(a)/Norm()/a.Norm() may result in values larger than 1 and smaller than -1 due to numerical rounding errors. -1-MYEPSILON causes NaN to be returned by acos, hence we check whether the value is smaller than -1 or greater than 1 and set to the limit if out of bounds.

This causes a wrong triangle to be taken due to the wrong SphereCenter being copied (comparing MYEPSILON to NAN)

File:

• molecuilder/src/vector.cpp (modified) (1 diff)

molecuilder/src/vector.cpp

@@ -259 +259 @@
 double Vector::Angle(const Vector *y) const
 {
-        return acos(this->ScalarProduct(y)/Norm()/y->Norm());
+  double angle = this->ScalarProduct(y)/Norm()/y->Norm();
+  // -1-MYEPSILON occured due to numerical imprecision, catch ...
+  //cout << Verbose(2) << "INFO: acos(-1) = " << acos(-1) << ", acos(-1+MYEPSILON) = " << acos(-1+MYEPSILON) << ", acos(-1-MYEPSILON) = " << acos(-1-MYEPSILON) << "." << endl;
+  if (angle < -1)
+    angle = -1;
+  if (angle > 1)
+    angle = 1;
+        return acos(angle);
 };