What is the difference between fix and if command

For example:. Use parentheses to group the expressions. In formulas, these operators are Boolean operators. AND: An empty set. The FIX statement is ignored and the calculation continues with a warning message. In FIX statements, members from the same dimension are always acted on as OR unless you specify otherwise. You must use these functions; FIX Can is not supported. Can be any statement, including block statements and further nested if statements.

Multiple if Note that there is no elseif in one word keyword in JavaScript. In general, it is a good practice to always use block statements, especially in code involving nested if statements:. Do not confuse the primitive Boolean values true and false with truthiness or falsiness of the Boolean object. Any value that is not false , undefined , null , 0 , -0 , NaN , or the empty string "" , and any object, including a Boolean object whose value is false , is considered truthy when used as the condition.

For example:. The unfix command is the only way to turn off a fix; simply specifying a new fix with a similar style will not turn off the first one. This is especially important to realize for integration fixes. Thus two time integrators would be in place!

If you specify a new fix with the same ID and style as an existing fix, the old fix is deleted and the new one is created presumably with new settings.

The fix modify command allows settings for some fixes to be reset. See the page for individual fixes for details. This allows the fix to continue on with its calculations in a restarted simulation. See the doc pages for individual fixes for info on which ones can be restarted. Some fixes calculate one of three styles of quantities: global, per-atom, or local, which can be used by other commands or output as described below. A global quantity is one or more system-wide values, e.

A per-atom quantity is one or more values per atom, e. Per-atom values are set to 0. Local quantities are calculated by each processor based on the atoms it owns, but there may be zero or more per atoms. Note that a single fix can produce either global or per-atom or local quantities or none at all , but not both global and per-atom. It can produce local quantities in tandem with global or per-atom quantities.

The fix page will explain. Global, per-atom, and local quantities each come in three kinds: a single scalar value, a vector of values, or a 2d array of values. The doc page for each fix describes the style and kind of values it produces, e.