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Optimized optimizedMultiply and optimizedAddMultiplied for cases of negative value of other and multiplier

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Gleb Minaev 2022-03-15 15:35:17 +03:00
parent ebd7f799ad
commit f86529d659
1 changed files with 42 additions and 17 deletions
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59
kmath-functions/src/commonMain/kotlin/space/kscience/kmath/functions/algebraicStub.kt
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@ -16,17 +16,11 @@ import space.kscience.kmath.operations.Group
* @receiver the multiplicand.
* @param other the multiplier.
* @return the difference.
* @author Gleb Minaev
*/
internal tailrec fun <C> Group<C>.optimizedMultiply(arg: C, other: Int): C =
when {
other == 0 -> zero
other == 1 -> arg
other == -1 -> -arg
other % 2 == 0 -> optimizedMultiply(arg + arg, other / 2)
other % 2 == 1 -> optimizedAddMultiplied(arg, arg + arg, other / 2)
other % 2 == -1 -> optimizedAddMultiplied(-arg, arg + arg, other / 2)
else -> error("Error in multiplication group instant by integer: got reminder by division by 2 different from 0, 1 and -1")
}
internal fun <C> Group<C>.optimizedMultiply(arg: C, other: Int): C =
if (other >= 0) optimizedMultiply(arg, other.toUInt())
else optimizedMultiply(arg, (-other).toUInt())
// TODO: Move receiver to context receiver
/**
@ -40,12 +34,43 @@ internal tailrec fun <C> Group<C>.optimizedMultiply(arg: C, other: Int): C =
* @author Gleb Minaev
*/
internal tailrec fun <C> Group<C>.optimizedAddMultiplied(base: C, arg: C, multiplier: Int): C =
if (multiplier >= 0) optimizedAddMultiplied(base, arg, multiplier.toUInt())
else optimizedAddMultiplied(base, arg, (-multiplier).toUInt())
// TODO: Move receiver to context receiver
/**
* Multiplication of element and integer.
*
* @receiver the multiplicand.
* @param other the multiplier.
* @return the difference.
* @author Gleb Minaev
*/
internal tailrec fun <C> Group<C>.optimizedMultiply(arg: C, other: UInt): C =
when {
multiplier == 0 -> base
multiplier == 1 -> base + arg
multiplier == -1 -> base - arg
multiplier % 2 == 0 -> optimizedAddMultiplied(base, arg + arg, multiplier / 2)
multiplier % 2 == 1 -> optimizedAddMultiplied(base + arg, arg + arg, multiplier / 2)
multiplier % 2 == -1 -> optimizedAddMultiplied(base + arg, arg + arg, multiplier / 2)
else -> error("Error in multiplication group instant by integer: got reminder by division by 2 different from 0, 1 and -1")
other == 0u -> zero
other == 1u -> arg
other % 2u == 0u -> optimizedMultiply(arg + arg, other / 2u)
other % 2u == 1u -> optimizedAddMultiplied(arg, arg + arg, other / 2u)
else -> error("Error in multiplication group instant by unsigned integer: got reminder by division by 2 different from 0 and 1")
}
// TODO: Move receiver to context receiver
/**
* Adds product of [arg] and [multiplier] to [base].
*
* @receiver the algebra to provide multiplication.
* @param base the augend.
* @param arg the multiplicand.
* @param multiplier the multiplier.
* @return sum of the augend [base] and product of the multiplicand [arg] and the multiplier [multiplier].
* @author Gleb Minaev
*/
internal tailrec fun <C> Group<C>.optimizedAddMultiplied(base: C, arg: C, multiplier: UInt): C =
when {
multiplier == 0u -> base
multiplier == 1u -> base + arg
multiplier % 2u == 0u -> optimizedAddMultiplied(base, arg + arg, multiplier / 2u)
multiplier % 2u == 1u -> optimizedAddMultiplied(base + arg, arg + arg, multiplier / 2u)
else -> error("Error in multiplication group instant by unsigned integer: got reminder by division by 2 different from 0 and 1")
}