represents the domain of real numbers, as in xReals.


  • xReals evaluates immediately if x is a numeric quantity.
  • Simplify[exprReals,assum] can be used to try to determine whether an expression corresponds to a real number under the given assumptions.
  • (x1|x2|)Reals and {x1,x2,}Reals test whether all xi are real numbers.
  • Within Simplify and similar functions, objects that satisfy inequalities are always assumed to be real.
  • Reals is output in StandardForm or TraditionalForm as TemplateBox[{}, Reals]. This typeset form can be input using reals.


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Basic Examples  (3)

is a real number:

If is a real number, so is :

Find real solutions of an equation:

Scope  (5)

Test domain membership of a numeric expression:

Make domain membership assumptions:

Specify the default domain over which a function should work:

Test whether several numbers are real numbers:

If any number is explicitly non-real, the result is False:

TraditionalForm formatting:

Properties & Relations  (3)

Reals contains Rationals, Integers, and Primes:

Reals is contained in Complexes:

Reals neither contains nor is contained in Algebraics:

Wolfram Research (1999), Reals, Wolfram Language function, (updated 2017).


Wolfram Research (1999), Reals, Wolfram Language function, (updated 2017).


Wolfram Language. 1999. "Reals." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2017.


Wolfram Language. (1999). Reals. Wolfram Language & System Documentation Center. Retrieved from


@misc{reference.wolfram_2024_reals, author="Wolfram Research", title="{Reals}", year="2017", howpublished="\url{}", note=[Accessed: 19-June-2024 ]}


@online{reference.wolfram_2024_reals, organization={Wolfram Research}, title={Reals}, year={2017}, url={}, note=[Accessed: 19-June-2024 ]}