strength reduction
An optimisation where a function of some systematicallychanging variable is calculated more efficiently by usingprevious values of the function. In aprocedural languagethis would apply to an expression involving a loop variableand in adeclarative language it would apply to the argumentof arecursive function. E.g.f x = ... (2**x) ... (f (x+1)) ... ==> f x = f' x (2**x) where f ' x z = ... z ... (f' (x+1) 2*z) ...Here the expensive operation (2**x) has been replaced by thecheaper 2*z in the recursive function f'. This maintains theinvariant that z = 2**x for any call to f'.
Last updated:1995-01-31
Nearby terms:
stream-oriented ♦STREAMS ♦strength reduction ♦STRESS ♦stress testing
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