# THETA

The THETA function computes the second angle, in radians, of a body-2 Euler angle rotation sequence (body-3, body-1, body-3) of marker I with respect to marker J.

THETA(I, J)

## Arguments

I
The marker whose rotational displacement is to be computed. Must be specified.
J
The marker with respect to which the rotational displacement is to be computed. This argument is optional. If omitted, it defaults to the ground coordinate system.

## Example

<Motion_Joint
id                  = "301001"
type                = "EXPRESSION"
val_type            = "D"
expr                = "STEP5(TIME,.2,0,.4,180D)"
joint_id            = "10010"
joint_type          = "R"
/>