The object of discussion is a three-bone arm; upArm, loArm, and hand.
If the arm is created in a linear fashion, with all three arms in one line, it is susceptible to erratic motion when being posed. The elbow can perform many funky tricks as you play with bone movement.
If the arm is created at a half-flexed position, with the elbow bent in a ninety-degree angle, it will behave as a human arm. The expected funk-factor was non-existant, despite my attempts to duplicate the error.
The bones are the same with the same joints. Therefore, the mathematics and corresponding matrix manipulation by the program should be the same. But why does the previous example behave erratically while the latter as though biological constraints (something Blender doesn’t handle yet) are active?
Struggling with basic concepts,