B313 Sequence: 1st Rotation (PSI)
Returns the first angle of rotation (in radians) associated with a body-fixed 313 rotation sequence from one coordinate system marker to another. This first rotation is referred to as the psi, 
, angle, and is used in association with the theta, 
, (2nd rotation) and phi, 
, (3rd rotation) angles.
, angle, and is used in association with the theta, , (2nd rotation) and phi, , (3rd rotation) angles.Positive angular displacement is determined by the right-hand rule.
Format
PSI (To Marker, From Marker)
Arguments
To Marker | (Required) The coordinate system marker whose rotation is being measured. |
From Marker | (Optional) The coordinate system marker with respect to which the rotation is being measured. If you don't specify this argument, it defaults to the global coordinate system. |
Example
The following example returns all the angles of rotation associated with a body-fixed 313 rotation sequence:
There are always at least two equivalent sets of rotation angles that yield the same final orientation. Using the above example, the same final orientation is achieved by using either of the following sets of rotation angles:
PSI (marker_T, marker_F) = | +90o | -90o |
THETA (marker_T, marker_F) = | -90o or | +90o |
PHI (marker_T, marker_F) = | +90o | -90o |