represents the domain of real numbers, as in .


  • evaluates immediately only if x is a numeric quantity.
  • Simplify[exprReals] can be used to try to determine whether an expression corresponds to a real number.
  • Within Simplify and similar functions, objects that satisfy inequalities are always assumed to be real.
  • Reals is output in TraditionalForm as .
Introduced in 1999
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