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Mathematica Teacher's Edition

Built-in Functions

Mathematical Functions

Numerical Functions

Re

Re[z] gives the real part of the complex number z.

Re[expr] is left unevaluated if expr is not a numeric quantity.
See The Mathematica Book on the web: Section 1.1.5 and Section 3.2.2.
See also: Im, Abs, Arg, ComplexExpand.

Further Examples