[MATH-554] Vector3D.crossProduct is sensitive to numerical cancellation

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.2
• Fix Version/s: 3.0

Environment

Linux, Sun JDK 1.5.0.22

• Assignee: Luc Maisonobe
• Reporter: Luc Maisonobe
• Created: 03/Apr/11 14:14
• Updated: 24/Mar/12 16:16
• Resolved: 03/Apr/11 14:33

Description

Cross product implementation uses the naive formulas (y1 z2 - y2 z1, ...). These formulas fail when vectors are almost colinear, like in the following example:

Vector3D v1 = new Vector3D(9070467121.0, 4535233560.0, 1);
Vector3D v2 = new Vector3D(9070467123.0, 4535233561.0, 1);
System.out.println(Vector3D.crossProduct(v1, v2));

The previous code displays

{ -1, 2, 0 }

instead of the correct answer

{ -1, 2, 1 }