NumberQ

Usage

• NumberQ[expr] gives True if expr is a number, and False otherwise.

Notes

• NumberQ[expr] returns False unless expr is manifestly a number (i.e., has head Complex, Integer, Rational or Real).

• NumberQ[Infinity] gives False.

• NumberQ[Overflow[ ]] and NumberQ[Underflow[ ]] give True.

• You can use NumberQ[x] ^= True to override the normal operation of NumberQ, and effectively define x to be a number.

• New in Version 1; modified in 3.