f := gp.stiff(gp)

Get the accumulated gridpoint effective stiffness.

This value is calculated during an update, based on the stiffness of all zones it is connected to, as well as other model elements such as interfaces or attach conditions.

The effective stiffness value is used during static (default) mode to determine the gridpoint inertial mass, as described in Mechanical Timestep Determination for Numerical Stability.

In dynamic mode, the effective stiffness is used to determine the critical timestep.

Returns:f - the effective gridpoint stiffness
Arguments:gp - a zone gridpoint pointer

[DR: please confirm link to mechtimestepdetermination above is going where wanted]