If Command

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.

Note:

• 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.
• Example: f(x) = If[x < 3, sin(x), x^2] yields a function that equals sin(x) for x < 3 and x² for x ≥ 3.
• See the section Boolean values for the symbols used in conditional statements.