Previous section-----Next section


RequiredEquations is an option for FindSwitchTime that specifies which equations, of a constraint that restrains more than one degree of freedom, are to be retained in seeking the switch time. RequiredEquations should be a two element list; the first element applies to the first set of equations of the TimeSwitch pair, the second element applies to the second set.
• Allowable values for each element are the following: an integer, a list of integers (1 through the number of degrees of freedom in the constraint), All, or Sum.
• The total number of equations specified must be equal to one plus the number of degrees of freedom constrained by the TimeSwitch.

• If All is given, all the constraints in the associated side of the TimeSwitch constraint are included.
Sum takes the sum of all equations in the associated side of the TimeSwitch constraint and uses the sum for a single constraint.
• Using the Sum setting can lead to a singularity.
• The normal method of specifying RequiredEquations is to specify All for one side and specify a single integer equation number for the other.
• The default setting is RequiredEquations->{All, Sum}.
• See also: TangentConstraint.