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NumberQ

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description

NumberQ[expr]
    gives True if expr is an explicit number (Integer, BigInt, Rational,
    Real, MPFR, or Complex), and False otherwise.  Symbolic constants
    such as Pi give False; use NumericQ for those.

Examples

All examples below are verified against the current Mathilda build.

In[1]:= MachineNumberQ[Sin[1000.]]
Out[1]= True

In[2]:= MachineNumberQ[Exp[1000.]]      (* overflows to +inf *)
Out[2]= False

In[3]:= MachineNumberQ[-29037945.290347]
Out[3]= True

In[4]:= MachineNumberQ[N[Pi, 30]]       (* MPFR, not machine *)
Out[4]= False

In[5]:= MachineNumberQ[1.0 + 2.0 I]
Out[5]= True

In[6]:= MachineNumberQ[1 + 2 I]         (* exact Gaussian integer *)
Out[6]= False

Implementation notes

builtin_numberq (src/core.c) returns True for an explicit number — EXPR_INTEGER, EXPR_REAL, EXPR_BIGINT, EXPR_MPFR (under USE_MPFR), or a Rational/Complex head — and False otherwise. (Contrast NumericQ, whose is_numeric_quantity helper also accepts symbolic constants like Pi and numeric-function calls.)

Attributes: Protected.

Implementation status

Stable — documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

References