# block.zone.stress.prin.dir

Syntax

v = block.zone.stress.prin.dir(bzp,prin,dir)

Get the zone principal stress directions.

Fills the array prin with the principal stress magnitudes and the array dir with the directions of the principal stresses. It also returns the principal stresses encoded as a vector (as does zone.stress.prin). prin indices 1, 2, and 3 are filled with the minimum, intermediate, and maximum principal stresses, respectively. dir indices 1-3 are the $$x-$$, $$y-$$, $$z$$-components of the minimum principal stress directions; 4-6 indicate the intermediate principal stress directions; and 7-9 indicate the maximum principal stress directions.

Note that compressive stresses are negative in 3DEC.

Returns: v - the zone principal stresses as a vector in minimum, intermediate, maximum order bzp - block zone pointer prin - pointer to an array of at least size 3, filled with the principal stress values dir - pointer to an array of at least size 9, filled with the principal stress directions