# gp.force.unbal.add

Syntax

Set (add to) the current unbalanced force at a gridpoint.

This adds to the current unbalanced force at a grid point. Extreme caution is required when using this function, as instability can result. The current unbalanced force in a grid point is cleared to zero after the equations of motion are applied, near the end of the cycle sequence. They are not cleared at the start of the cycle sequence.

Note that for the purpose of modifiers the current value is treated as a zero vector.

In general it is not necessary to call this function. Instead use either a fish or fish-local multiplier to an applied boundary condition, or the gp.force.load intrinsic.

See also the FISH intrinsics gp.force.unbal and gp.force.unbal.current.

Returns: v - value to add to the current unbalanced force vector gp - grid point pointer

Component Access

gp.force.unbal.add (gp)->x := f

Set (add to) the current $$x$$-component of the unbalanced force at a gridpoint.

Returns: f - $$x$$-component of the value to add to the current unbalanced force vector gp - grid point pointer

Access other vector components ($$y$$, $$z$$) by substituting the component name where $$x$$ appears above. See Member Access Operator for information about accessing members from data types using ->.

Deprecated Component Access

Component access by adding an optional integer in the function arguments (gp.force.unbal.add(gp,<int>)) is deprecated. It remains available but will not be supported in future versions. See Component Access with Integers in FISH on the Deprecated Commands and FISH page for details.

This is hidden. Added to include remaining vector component access functions for inline help.