PHI
The PHI function calculates the third angle (in radians) of a body-fixed-3-1-3 Euler rotation sequence between markers i and j. Marker j defaults to the global coordinate system if it is not specified. See Figure 8 for a schematic description of the body-fixed-3-1-3 Euler rotation sequence.
Format
PHI(i[,j])
Arguments
i | The marker whose rotations are being sought. |
j | The marker with respect to which the rotations are being measured. |
Examples
REQUEST/1, F2=PHI(222,434)
This REQUEST statement outputs the phi angle between Markers 222 and 434 in its second column.
See other Displacement measures available.
Figure 8 Body-fixed-3-1-3 Euler Angles
 | The body-fixed-3-1-3 sequence is started by rotating counterclockwise the initial system of axes, xyz, by an angle  about the z-axis. The resultant axes are labeled  . (Notice that z coincides with  .)In the second stage the intermediate axes,  , are rotated counterclockwise about the -axis by an angle  . The new resultant planes are labelled  . The  - axis is at the intersection of the xy and  planes and is known as the line of nodes. (Notice that  coincides with  .)In the final rotation, the  axes are rotated counterclockwise by an angle  about the  -axis to produce the x' y' z' axes, which is the desired final direction. (Notice that  coincides with z'.) |