oldEmptyBehaviour Controls the operation+ and operation- behaviour for Scilab

## Syntax

    oldEmptyBehaviour(behaviour)

## Arguments

behaviour

  a single string amongst `"on"`, `"off"` or `"query"`. The behaviour mode for operation+ and operation-

## Description

Controls the behaviour of the empty matrix addition and subtraction. On versions prior to scilab-6.0.0, adding or subtracting and empty matrix to any other value `val` would return `val`.

If `behaviour == "off"`, adding or subtracting the empty matrix will yield to the empty matrix. This is the default behaviour of scilab after version 6.0.0.

If `behaviour == "on"`, activates the behaviour prior to scilab-6.0.0.

If `behaviour == "query"`, returns the current value (`"on"` or `"off"`) for the `oldEmptyBehaviour` tag.

## Examples

    // Get the current behaviour
    behaviour = oldEmptyBehaviour("query");

    // These will return empty
    oldEmptyBehaviour("off");
    1 + []
    "Test string" + []
    [] - int8(1)
    [] - %s

    // These will leave the other operand unchanged
    oldEmptyBehaviour("on");
    1 + [] // returns 1
    "Test string" + [] // returns "Test string"
    [] - int8(1) // returns int8(1)
    [] - %s // returns %s

    // Get back to the saved behaviour
    oldEmptyBehaviour(behaviour)

## See also

- warning for the warning behaviour on operation+ and operation-
- plus for the behaviour of the operation+.
- minus for the behaviour of the operation-.