Condition


is a pattern which matches only if the evaluation of test yields True.


represents a rule which applies only if the evaluation of test yields True.


is a definition to be used only if test yields True.

DetailsDetails

  • All pattern variables used in test must also appear in patt.
  • lhs:=Module[{vars},rhs/;test] allows local variables to be shared between test and rhs. You can use the same construction with Block and With. »

ExamplesExamplesopen allclose all

Basic Examples  (2)Basic Examples  (2)

Make a definition with the condition that x should be positive:

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Replace all elements which satisfy the condition of being negative:

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Introduced in 1988
(1.0)