An optimisation where a function of some systematically changing variable is calculated more efficiently by using previous values of the function. In a ef="module.php?name=Lexikon&file=search&eid=1&query=procedural language">procedural language this would apply to an expression involving a loop variable and in a ef="module.php?name=Lexikon&file=search&eid=1&query=declarative language">declarative language it would apply to the argument of a ef="module.php?name=Lexikon&file=search&eid=1&query=recursive">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 Here the expensive operation (2**x) has been replaced by the cheaper 2*z in the recursive function f' .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' . (1995-01-31)

e="border-width:thin; border-color:#333333; border-style:dashed; padding:5px;" align="left">In addition suitable contents:
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