# Difference between revisions of "If Command"

##### Command Categories (All commands)

If[ <Condition>, <Object> ]
Yields a copy of the object if the condition evaluates to true, and an undefined object if it evaluates to false.
If[ <Condition>, <Object a>, <Object b> ]
Yields a copy of object a if the condition evaluates to true, and a copy of object b if it evaluates to false.
 Warning: Both objects must be of the same type.

### Conditional Functions

The If command can be used to create conditional functions. Such conditional functions may be used as arguments in any command that takes a function argument, such as Derivative, Integral, and Intersect.

Examples:
• `f(x) = If[x < 3, sin(x), x^2]` yields a piecewise function that equals sin(x) for x < 3 and x2 for x ≥ 3.
• `f(x) = If[0 <= x <= 3, sin(x) ]` yields a function that equals sin(x) for x between 0 and 3 (and undefined otherwise).
Note: See section: Boolean values for the symbols used in conditional statements.
Note: Derivative of If[condition, f(x), g(x)] gives If[condition, f'(x), g'(x)]. It does not do any evaluation of limits at the critical points.

## If Command in Scripting

If command can be used in scripts to perform different actions under certain conditions.

Example: Let n be a number, and A a point. The command `If[Mod[n, 7] == 0, SetCoords[A, n, 0], SetCoords[A, n, 1]]` modifies the coordinates of point A according to the given condition. In this case it would be easier to use ` SetCoords[A, n, If[Mod[n, 7] == 0,0,1]]`.

Note that arguments of If must be Objects or Scripting Commands, not assignments. Syntax `b=If[a>1,2,3]` is correct, but b=2 or b=3 would not be accepted as parameters of If.

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