Skip to content

MachineNumberQ

Status: Stable

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

Description

MachineNumberQ[expr] gives True if expr is a machine-precision real or complex number, and False otherwise.

Examples (10)

Every input below was run against the current Mathilda build and its output recorded.

Basic examples (4)

In[1]:= StringQ["AbC"]
Out[1]= True

In[2]:= StringQ[""]
Out[2]= True

In[3]:= StringQ[123]
Out[3]= False

In[4]:= StringQ[] StringQ::argx: StringQ called with 0 arguments; 1 argument is expected.

Scope (6)

In[5]:= MachineNumberQ[Sin[1000.]]
Out[5]= True

Overflows to +inf

In[6]:= MachineNumberQ[Exp[1000.]]
Out[6]= False

In[7]:= MachineNumberQ[-29037945.290347]
Out[7]= True

MPFR, not machine

In[8]:= MachineNumberQ[N[Pi, 30]]
Out[8]= False

In[9]:= MachineNumberQ[1.0 + 2.0 I]
Out[9]= True

Exact Gaussian integer

In[10]:= MachineNumberQ[1 + 2 I]
Out[10]= False

Algorithm

Mathilda — numeric evaluation implementation.

See numeric.h for the module-level overview and extensibility notes.

This file implements N[expr] / N[expr, prec]. Phase 1 targets machine-precision IEEE doubles; Phase 2 (gated behind USE_MPFR) adds MPFR arbitrary precision. Phase-2 extension points are marked with an inline "Phase 2" marker so the eventual additions are obvious.

Implementation notes

builtin_machinenumberq (src/numeric.c) returns True when the argument is a finite EXPR_REAL (via is_machine_real_leaf, which checks EXPR_REAL and isfinite), or a Complex whose real and imaginary parts are both finite machine reals; otherwise False. Exact integers/rationals and arbitrary-precision EXPR_MPFR values are not machine numbers.

Attributes: Protected.

References

See also: AtomQ, NumberQ, IntegerQ, StringQ, Complex, ExactNumberQ