Excel: Volatile functions

The volatility of a function (either worksheet functions or user defined VBA functions) affects when the the function is called for formula recalculation purposes.

A volatile function is always called when

• The value of any cell changes on the worksheet
• One of the F9 recalculation shortcut keys is pressed.

In contrast, the non-volatile function are only called by pressing

• ctrl+alt+F9
• ctrl+alt+shift+F9

Volatile worksheet functions include

• cell
• info (for some arguments)
• now, today
• offset
• randBetween
• sumIf
• indirect

A user defined VBA function can be marked (in Excel, that is) to be volatile with application.volatile.