39 lines
1.5 KiB
Haskell
39 lines
1.5 KiB
Haskell
-- |
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-- Module: Math.NumberTheory.Powers.Integer
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-- Copyright: (c) 2011-2014 Daniel Fischer
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-- Licence: MIT
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-- Maintainer: Daniel Fischer <daniel.is.fischer@googlemail.com>
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-- Stability: Provisional
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-- Portability: Non-portable (GHC extensions)
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--
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-- Potentially faster power function for 'Integer' base and 'Int'
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-- or 'Word' exponent.
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--
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{-# LANGUAGE Safe #-}
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module Math.NumberTheory.Powers.Integer
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{-# DEPRECATED "It is no faster than (^)" #-}
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( integerPower
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, integerWordPower
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) where
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-- | Power of an 'Integer' by the left-to-right repeated squaring algorithm.
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-- This needs two multiplications in each step while the right-to-left
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-- algorithm needs only one multiplication for 0-bits, but here the
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-- two factors always have approximately the same size, which on average
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-- gains a bit when the result is large.
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--
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-- For small results, it is unlikely to be any faster than '(^)', quite
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-- possibly slower (though the difference shouldn't be large), and for
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-- exponents with few bits set, the same holds. But for exponents with
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-- many bits set, the speedup can be significant.
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--
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-- /Warning:/ No check for the negativity of the exponent is performed,
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-- a negative exponent is interpreted as a large positive exponent.
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integerPower :: Integer -> Int -> Integer
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integerPower = (^)
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{-# DEPRECATED integerPower "Use (^) instead" #-}
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-- | Same as 'integerPower', but for exponents of type 'Word'.
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integerWordPower :: Integer -> Word -> Integer
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integerWordPower = (^)
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{-# DEPRECATED integerWordPower "Use (^) instead" #-}
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