meaning of strength reduction
1. strength reduction An optimisation where a function of some systematically changing variable is calculated more efficiently by using previous values of the function. In a procedural language this would apply to an expression involving a loop variable and in a declarative language it would apply to the argument of a recursive 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 Here the expensive operation 2**x has been replaced by the cheaper 2*z in the recursive function f. This maintains the invariant that z = 2**x for any call to f.
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