Restructured Polynomial

This commit is contained in:
Gleb Minaev 2022-03-03 20:45:35 +03:00
parent c80f70fe0f
commit 2483c56f1c
8 changed files with 846 additions and 154 deletions

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@ -0,0 +1,354 @@
/*
* Copyright 2018-2021 KMath contributors.
* Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
*/
package space.kscience.kmath.functions
import space.kscience.kmath.operations.*
import kotlin.js.JsName
import kotlin.jvm.JvmName
/**
* Abstraction of polynomials.
*/
public interface AbstractPolynomial<C>
/**
* Abstraction of ring of polynomials of type [P] over ring of constants of type [C].
*/
@Suppress("INAPPLICABLE_JVM_NAME", "PARAMETER_NAME_CHANGED_ON_OVERRIDE")
public interface AbstractPolynomialSpace<C, P: AbstractPolynomial<C>> : Ring<P> {
// region Constant-integer relation
/**
* Returns sum of the constant and the integer represented as constant (member of underlying ring).
*
* The operation is equivalent to adding [other] copies of unit of underlying ring to [this].
*/
@JvmName("constantIntPlus")
public operator fun C.plus(other: Int): C
/**
* Returns difference between the constant and the integer represented as constant (member of underlying ring).
*
* The operation is equivalent to subtraction [other] copies of unit of underlying ring from [this].
*/
@JvmName("constantIntMinus")
public operator fun C.minus(other: Int): C
/**
* Returns product of the constant and the integer represented as constant (member of underlying ring).
*
* The operation is equivalent to sum of [other] copies of [this].
*/
@JvmName("constantIntTimes")
public operator fun C.times(other: Int): C
// endregion
// region Integer-constant relation
/**
* Returns sum of the integer represented as constant (member of underlying ring) and the constant.
*
* The operation is equivalent to adding [this] copies of unit of underlying ring to [other].
*/
@JvmName("intConstantPlus")
public operator fun Int.plus(other: C): C
/**
* Returns difference between the integer represented as constant (member of underlying ring) and the constant.
*
* The operation is equivalent to subtraction [this] copies of unit of underlying ring from [other].
*/
@JvmName("intConstantMinus")
public operator fun Int.minus(other: C): C
/**
* Returns product of the integer represented as constant (member of underlying ring) and the constant.
*
* The operation is equivalent to sum of [this] copies of [other].
*/
@JvmName("intConstantTimes")
public operator fun Int.times(other: C): C
// endregion
// region Polynomial-integer relation
/**
* Returns sum of the constant and the integer represented as polynomial.
*
* The operation is equivalent to adding [other] copies of unit polynomial to [this].
*/
public operator fun P.plus(other: Int): P = optimizedAddMultiplied(this, one, other)
/**
* Returns difference between the constant and the integer represented as polynomial.
*
* The operation is equivalent to subtraction [other] copies of unit polynomial from [this].
*/
public operator fun P.minus(other: Int): P = optimizedAddMultiplied(this, one, -other)
/**
* Returns product of the constant and the integer represented as polynomial.
*
* The operation is equivalent to sum of [other] copies of [this].
*/
public operator fun P.times(other: Int): P = optimizedMultiply(this, other)
// endregion
// region Integer-polynomial relation
/**
* Returns sum of the integer represented as polynomial and the constant.
*
* The operation is equivalent to adding [this] copies of unit polynomial to [other].
*/
public operator fun Int.plus(other: P): P = optimizedAddMultiplied(other, one, this)
/**
* Returns difference between the integer represented as polynomial and the constant.
*
* The operation is equivalent to subtraction [this] copies of unit polynomial from [other].
*/
public operator fun Int.minus(other: P): P = optimizedAddMultiplied(-other, one, this)
/**
* Returns product of the integer represented as polynomial and the constant.
*
* The operation is equivalent to sum of [this] copies of [other].
*/
public operator fun Int.times(other: P): P = optimizedMultiply(other, this)
// endregion
// region Constant-constant relation
/**
* Returns the same constant.
*/
@JvmName("constantUnaryPlus")
@JsName("constantUnaryPlus")
public operator fun C.unaryPlus(): C = this
/**
* Returns negation of the constant.
*/
@JvmName("constantUnaryMinus")
@JsName("constantUnaryMinus")
public operator fun C.unaryMinus(): C
/**
* Returns sum of the constants.
*/
@JvmName("constantPlus")
@JsName("constantPlus")
public operator fun C.plus(other: C): C
/**
* Returns difference of the constants.
*/
@JvmName("constantMinus")
@JsName("constantMinus")
public operator fun C.minus(other: C): C
/**
* Returns product of the constants.
*/
@JvmName("constantTimes")
@JsName("constantTimes")
public operator fun C.times(other: C): C
/**
* Check if the instant is zero constant.
*/
@JvmName("constantIsZero")
public fun C.isZero(): Boolean
/**
* Check if the instant is NOT zero constant.
*/
@JvmName("constantIsNotZero")
public fun C.isNotZero(): Boolean
/**
* Check if the instant is unit constant.
*/
@JvmName("constantIsOne")
public fun C.isOne(): Boolean
/**
* Check if the instant is NOT unit constant.
*/
@JvmName("constantIsNotOne")
public fun C.isNotOne(): Boolean
/**
* Check if the instant is minus unit constant.
*/
@JvmName("constantIsMinusOne")
public fun C.isMinusOne(): Boolean
/**
* Check if the instant is NOT minus unit constant.
*/
@JvmName("constantIsNotMinusOne")
public fun C.isNotMinusOne(): Boolean
// endregion
// region Constant-polynomial relation
/**
* Returns sum of the constant represented as polynomial and the polynomial.
*/
public operator fun C.plus(other: P): P
/**
* Returns difference between the constant represented as polynomial and the polynomial.
*/
public operator fun C.minus(other: P): P
/**
* Returns product of the constant represented as polynomial and the polynomial.
*/
public operator fun C.times(other: P): P
// endregion
// region Polynomial-constant relation
/**
* Returns sum of the constant represented as polynomial and the polynomial.
*/
public operator fun P.plus(other: C): P
/**
* Returns difference between the constant represented as polynomial and the polynomial.
*/
public operator fun P.minus(other: C): P
/**
* Returns product of the constant represented as polynomial and the polynomial.
*/
public operator fun P.times(other: C): P
// endregion
// region Polynomial-polynomial relation
/**
* Returns the same polynomial.
*/
public override operator fun P.unaryPlus(): P = this
/**
* Returns negation of the polynomial.
*/
public override operator fun P.unaryMinus(): P
/**
* Returns sum of the polynomials.
*/
public override operator fun P.plus(other: P): P
/**
* Returns difference of the polynomials.
*/
public override operator fun P.minus(other: P): P
/**
* Returns product of the polynomials.
*/
public override operator fun P.times(other: P): P
/**
* Check if the instant is zero polynomial.
*/
public fun P.isZero(): Boolean = this == zero
/**
* Check if the instant is NOT zero polynomial.
*/
public fun P.isNotZero(): Boolean = this != zero
/**
* Check if the instant is unit polynomial.
*/
public fun P.isOne(): Boolean = this == one
/**
* Check if the instant is NOT unit polynomial.
*/
public fun P.isNotOne(): Boolean = this != one
/**
* Check if the instant is minus unit polynomial.
*/
public fun P.isMinusOne(): Boolean = this == -one
/**
* Check if the instant is NOT minus unit polynomial.
*/
public fun P.isNotMinusOne(): Boolean = this != -one
/**
* Instance of zero polynomial (zero of the polynomial ring).
*/
override val zero: P
/**
* Instance of unit polynomial (unit of the polynomial ring).
*/
override val one: P
/**
* Checks equality of the polynomials.
*/
@Suppress("EXTENSION_SHADOWED_BY_MEMBER", "CovariantEquals")
public fun P.equals(other: P): Boolean
// endregion
// Not sure is it necessary...
// region Polynomial properties
/**
* Degree of the polynomial, [see also](https://en.wikipedia.org/wiki/Degree_of_a_polynomial). If the polynomial is
* zero, degree is -1.
*/
public val P.degree: Int
/**
* Checks if the instant is constant polynomial (of degree no more than 0) over considered ring.
*/
public fun P.isConstant(): Boolean = degree <= 0
/**
* Checks if the instant is **not** constant polynomial (of degree no more than 0) over considered ring.
*/
public fun P.isNotConstant(): Boolean = !isConstant()
/**
* Checks if the instant is constant non-zero polynomial (of degree no more than 0) over considered ring.
*/
public fun P.isNonZeroConstant(): Boolean = degree == 0
/**
* Checks if the instant is **not** constant non-zero polynomial (of degree no more than 0) over considered ring.
*/
public fun P.isNotNonZeroConstant(): Boolean = !isNonZeroConstant()
/**
* If polynomial is a constant polynomial represents and returns it as constant.
* Otherwise, (when the polynomial is not constant polynomial) returns `null`.
*/
public fun P.asConstantOrNull(): C?
/**
* If polynomial is a constant polynomial represents and returns it as constant.
* Otherwise, (when the polynomial is not constant polynomial) raises corresponding exception.
*/
public fun P.asConstant(): C = asConstantOrNull() ?: error("Can not represent non-constant polynomial as a constant")
// endregion
// region Legacy of Ring interface
override fun add(left: P, right: P): P = left + right
override fun multiply(left: P, right: P): P = left * right
// endregion
public companion object {
// TODO: All of this should be moved to algebraic structures' place for utilities
// TODO: Move receiver to context receiver
/**
* Multiplication of element and integer.
*
* @receiver the multiplicand.
* @param other the multiplier.
* @return the difference.
*/
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")
}
// 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: Int): 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")
}
}
}

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@ -117,16 +117,16 @@ public fun <T : Comparable<T>> PiecewisePolynomial(
* Return a value of polynomial function with given [ring] a given [arg] or null if argument is outside piecewise
* definition.
*/
public fun <T : Comparable<T>, C : Ring<T>> PiecewisePolynomial<T>.value(ring: C, arg: T): T? =
findPiece(arg)?.value(ring, arg)
public fun <T : Comparable<T>, C : Ring<T>> PiecewisePolynomial<T>.substitute(ring: C, arg: T): T? =
findPiece(arg)?.substitute(ring, arg)
/**
* Convert this polynomial to a function returning nullable value (null if argument is outside piecewise range).
*/
public fun <T : Comparable<T>, C : Ring<T>> PiecewisePolynomial<T>.asFunction(ring: C): (T) -> T? = { value(ring, it) }
public fun <T : Comparable<T>, C : Ring<T>> PiecewisePolynomial<T>.asFunction(ring: C): (T) -> T? = { substitute(ring, it) }
/**
* Convert this polynomial to a function using [defaultValue] for arguments outside the piecewise range.
*/
public fun <T : Comparable<T>, C : Ring<T>> PiecewisePolynomial<T>.asFunction(ring: C, defaultValue: T): (T) -> T =
{ value(ring, it) ?: defaultValue }
{ substitute(ring, it) ?: defaultValue }

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@ -5,128 +5,371 @@
package space.kscience.kmath.functions
import space.kscience.kmath.misc.UnstableKMathAPI
import space.kscience.kmath.functions.AbstractPolynomialSpace.Companion.optimizedAddMultiplied
import space.kscience.kmath.functions.AbstractPolynomialSpace.Companion.optimizedMultiply
import space.kscience.kmath.operations.*
import kotlin.contracts.InvocationKind
import kotlin.contracts.contract
import kotlin.jvm.JvmName
import kotlin.math.max
import kotlin.math.pow
import kotlin.math.min
/**
* Polynomial coefficients model without fixation on specific context they are applied to.
*
* @param coefficients constant is the leftmost coefficient.
*/
public class Polynomial<out T>(public val coefficients: List<T>) {
public class Polynomial<T>(public val coefficients: List<T>) : AbstractPolynomial<T> {
override fun toString(): String = "Polynomial$coefficients"
// public companion object {
// /**
// * Default name of variables used in string representations.
// *
// * @see Polynomial.toString
// */
// public var defaultVariableName: String = "x"
//
// /**
// * Represents result of division with remainder.
// */
// public data class DividingResult<C>(
// val quotient: Polynomial<C>,
// val reminder: Polynomial<C>
// )
// }
}
/**
* Returns a [Polynomial] instance with given [coefficients].
* Represents internal [Polynomial] errors.
*/
internal class PolynomialError(message: String): Error(message)
// region Constructors and converters
/**
* Returns a [Polynomial] instance with given [coefficients]. The collection of coefficients will be reversed if
* [reverse] parameter is true.
*/
@Suppress("FunctionName")
public fun <T> Polynomial(vararg coefficients: T): Polynomial<T> = Polynomial(coefficients.toList())
public fun <T> Polynomial(coefficients: List<T>, reverse: Boolean = false): Polynomial<T> =
Polynomial(with(coefficients) { if (reverse) reversed() else this })
/**
* Evaluates the value of the given double polynomial for given double argument.
* Returns a [Polynomial] instance with given [coefficients]. The collection of coefficients will be reversed if
* [reverse] parameter is true.
*/
public fun Polynomial<Double>.value(arg: Double): Double = coefficients.reduceIndexed { index, acc, c ->
acc + c * arg.pow(index)
}
@Suppress("FunctionName")
public fun <T> Polynomial(vararg coefficients: T, reverse: Boolean = false): Polynomial<T> =
Polynomial(with(coefficients) { if (reverse) reversed() else toList() })
public fun <T> T.asPolynomial() : Polynomial<T> = Polynomial(listOf(this))
// endregion
/**
* Evaluates the value of the given polynomial for given argument.
* https://en.wikipedia.org/wiki/Horner%27s_method
*/
public fun <T, C : Ring<T>> Polynomial<T>.value(ring: C, arg: T): T = ring {
if (coefficients.isEmpty()) return@ring zero
var result: T = coefficients.last()
for (j in coefficients.size - 2 downTo 0) {
result = (arg * result) + coefficients[j]
}
return result
}
/**
* Represent the polynomial as a regular context-less function.
*/
public fun <T, C : Ring<T>> Polynomial<T>.asFunction(ring: C): (T) -> T = { value(ring, it) }
/**
* Create a polynomial witch represents differentiated version of this polynomial
*/
@UnstableKMathAPI
public fun <T, A> Polynomial<T>.differentiate(
algebra: A,
): Polynomial<T> where A : Ring<T>, A : NumericAlgebra<T> = algebra {
Polynomial(coefficients.drop(1).mapIndexed { index, t -> number(index) * t })
}
/**
* Create a polynomial witch represents indefinite integral version of this polynomial
*/
@UnstableKMathAPI
public fun <T, A> Polynomial<T>.integrate(
algebra: A,
): Polynomial<T> where A : Field<T>, A : NumericAlgebra<T> = algebra {
val integratedCoefficients = buildList(coefficients.size + 1) {
add(zero)
coefficients.forEachIndexed{ index, t -> add(t / (number(index) + one)) }
}
Polynomial(integratedCoefficients)
}
/**
* Compute a definite integral of a given polynomial in a [range]
*/
@UnstableKMathAPI
public fun <T : Comparable<T>> Polynomial<T>.integrate(
algebra: Field<T>,
range: ClosedRange<T>,
): T = algebra {
val integral = integrate(algebra)
integral.value(algebra, range.endInclusive) - integral.value(algebra, range.start)
}
/**
* Space of polynomials.
* Space of polynomials constructed over ring.
*
* @param T the type of operated polynomials.
* @param C the intersection of [Ring] of [T] and [ScaleOperations] of [T].
* @param ring the [C] instance.
* @param C the type of constants. Polynomials have them as a coefficients in their terms.
* @param A type of underlying ring of constants. It's [Ring] of [C].
* @param ring underlying ring of constants of type [A].
*/
public class PolynomialSpace<T, C>(
private val ring: C,
) : Group<Polynomial<T>>, ScaleOperations<Polynomial<T>> where C : Ring<T>, C : ScaleOperations<T> {
override val zero: Polynomial<T> = Polynomial(emptyList())
@Suppress("INAPPLICABLE_JVM_NAME") // KT-31420
public open class PolynomialSpace<C, A : Ring<C>>(
public val ring: A,
) : AbstractPolynomialSpace<C, Polynomial<C>>{
// region Constant-integer relation
@JvmName("constantIntPlus")
public override operator fun C.plus(other: Int): C = ring { optimizedAddMultiplied(this@plus, one, other) }
@JvmName("constantIntMinus")
public override operator fun C.minus(other: Int): C = ring { optimizedAddMultiplied(this@minus, one, -other) }
@JvmName("constantIntTimes")
public override operator fun C.times(other: Int): C = ring { optimizedMultiply(this@times, other) }
// endregion
override fun Polynomial<T>.unaryMinus(): Polynomial<T> = ring {
// region Integer-constant relation
@JvmName("intConstantPlus")
public override operator fun Int.plus(other: C): C = ring { optimizedAddMultiplied(other, one, this@plus) }
@JvmName("intConstantMinus")
public override operator fun Int.minus(other: C): C = ring { optimizedAddMultiplied(-other, one, this@minus) }
@JvmName("intConstantTimes")
public override operator fun Int.times(other: C): C = ring { optimizedMultiply(other, this@times) }
// endregion
// region Polynomial-integer relation
public override operator fun Polynomial<C>.plus(other: Int): Polynomial<C> =
if (other == 0) this
else
Polynomial(
coefficients
.toMutableList()
.apply {
if (isEmpty()) this[0] = ring.zero + other
else this[0] = this[0]!! + other
}
)
public override operator fun Polynomial<C>.minus(other: Int): Polynomial<C> =
if (other == 0) this
else
Polynomial(
coefficients
.toMutableList()
.apply {
if (isEmpty()) this[0] = ring.zero - other
else this[0] = this[0]!! - other
}
)
public override operator fun Polynomial<C>.times(other: Int): Polynomial<C> =
if (other == 0) zero
else Polynomial(
coefficients
.subList(0, degree + 1)
.map { it * other }
)
// endregion
// region Integer-polynomial relation
public override operator fun Int.plus(other: Polynomial<C>): Polynomial<C> =
if (this == 0) other
else
Polynomial(
other.coefficients
.toMutableList()
.apply {
if (isEmpty()) this[0] = ring.zero + this@plus
else this[0] = this[0]!! + this@plus
}
)
public override operator fun Int.minus(other: Polynomial<C>): Polynomial<C> =
if (this == 0) other
else
Polynomial(
other.coefficients
.toMutableList()
.apply {
if (isEmpty()) this[0] = ring.zero - this@minus
else this[0] = this[0]!! - this@minus
}
)
public override operator fun Int.times(other: Polynomial<C>): Polynomial<C> =
if (this == 0) zero
else Polynomial(
other.coefficients
.subList(0, other.degree + 1)
.map { it * this }
)
// endregion
// region Constant-constant relation
@JvmName("constantUnaryMinus")
public override operator fun C.unaryMinus(): C = ring { -this@unaryMinus }
@JvmName("constantPlus")
public override operator fun C.plus(other: C): C = ring { this@plus + other }
@JvmName("constantMinus")
public override operator fun C.minus(other: C): C = ring { this@minus - other }
@JvmName("constantTimes")
public override operator fun C.times(other: C): C = ring { this@times * other }
@JvmName("constantIsZero")
public override fun C.isZero(): Boolean = ring { this == zero }
@JvmName("constantIsNotZero")
public override fun C.isNotZero(): Boolean = ring { this != zero }
@JvmName("constantIsOne")
public override fun C.isOne(): Boolean = ring { this == one }
@JvmName("constantIsNotOne")
public override fun C.isNotOne(): Boolean = ring { this != one }
@JvmName("constantIsMinusOne")
public override fun C.isMinusOne(): Boolean = ring { this == -one }
@JvmName("constantIsNotMinusOne")
public override fun C.isNotMinusOne(): Boolean = ring { this != -one }
// endregion
// region Constant-polynomial relation
public override operator fun C.plus(other: Polynomial<C>): Polynomial<C> =
with(other.coefficients) {
if (isEmpty()) Polynomial(listOf(this@plus))
else Polynomial(
toMutableList()
.apply {
this[0] += this@plus
}
)
}
// if (degree == -1) UnivariatePolynomial(other) else UnivariatePolynomial(
// listOf(coefficients[0] + other) + coefficients.subList(1, degree + 1)
// )
public override operator fun C.minus(other: Polynomial<C>): Polynomial<C> =
with(other.coefficients) {
if (isEmpty()) Polynomial(listOf(-this@minus))
else Polynomial(
toMutableList()
.apply {
this[0] -= this@minus
}
)
}
// if (degree == -1) UnivariatePolynomial(other) else UnivariatePolynomial(
// listOf(coefficients[0] + other) + coefficients.subList(1, degree + 1)
// )
public override operator fun C.times(other: Polynomial<C>): Polynomial<C> =
Polynomial(
other.coefficients
// .subList(0, other.degree + 1)
.map { it * this }
)
// endregion
// region Polynomial-constant relation
public override operator fun Polynomial<C>.plus(other: C): Polynomial<C> =
if (other.isZero()) this
else with(coefficients) {
if (isEmpty()) Polynomial(listOf(other))
else Polynomial(
toMutableList()
.apply {
this[0] += other
}
)
}
// if (degree == -1) UnivariatePolynomial(other) else UnivariatePolynomial(
// listOf(coefficients[0] + other) + coefficients.subList(1, degree + 1)
// )
public override operator fun Polynomial<C>.minus(other: C): Polynomial<C> =
with(coefficients) {
if (isEmpty()) Polynomial(listOf(other))
else Polynomial(
toMutableList()
.apply {
this[0] -= other
}
)
}
// if (degree == -1) UnivariatePolynomial(-other) else UnivariatePolynomial(
// listOf(coefficients[0] - other) + coefficients.subList(1, degree + 1)
// )
public override operator fun Polynomial<C>.times(other: C): Polynomial<C> =
Polynomial(
coefficients
// .subList(0, degree + 1)
.map { it * other }
)
// endregion
// region Polynomial-polynomial relation
public override operator fun Polynomial<C>.unaryMinus(): Polynomial<C> =
Polynomial(coefficients.map { -it })
}
override fun add(left: Polynomial<T>, right: Polynomial<T>): Polynomial<T> {
val dim = max(left.coefficients.size, right.coefficients.size)
return ring {
Polynomial(List(dim) { index ->
left.coefficients.getOrElse(index) { zero } + right.coefficients.getOrElse(index) { zero }
})
public override operator fun Polynomial<C>.plus(other: Polynomial<C>): Polynomial<C> =
Polynomial(
(0..max(degree, other.degree))
.map {
when {
it > degree -> other.coefficients[it]
it > other.degree -> coefficients[it]
else -> coefficients[it] + other.coefficients[it]
}
}
.ifEmpty { listOf(ring.zero) }
)
public override operator fun Polynomial<C>.minus(other: Polynomial<C>): Polynomial<C> =
Polynomial(
(0..max(degree, other.degree))
.map {
when {
it > degree -> -other.coefficients[it]
it > other.degree -> coefficients[it]
else -> coefficients[it] - other.coefficients[it]
}
}
.ifEmpty { listOf(ring.zero) }
)
public override operator fun Polynomial<C>.times(other: Polynomial<C>): Polynomial<C> {
val thisDegree = degree
val otherDegree = other.degree
return when {
thisDegree == -1 -> this
otherDegree == -1 -> other
else ->
Polynomial(
(0..(thisDegree + otherDegree))
.map { d ->
(max(0, d - otherDegree)..(min(thisDegree, d)))
.map { coefficients[it] * other.coefficients[d - it] }
.reduce { acc, rational -> acc + rational }
}
)
}
}
override fun scale(a: Polynomial<T>, value: Double): Polynomial<T> =
ring { Polynomial(List(a.coefficients.size) { index -> a.coefficients[index] * value }) }
public override fun Polynomial<C>.isZero(): Boolean = coefficients.all { it.isZero() }
public override fun Polynomial<C>.isNotZero(): Boolean = coefficients.any { it.isNotZero() }
public override fun Polynomial<C>.isOne(): Boolean =
with(coefficients) { isNotEmpty() && asSequence().withIndex().any { (index, c) -> if (index == 0) c.isOne() else c.isZero() } } // TODO: It's better to write new methods like `anyIndexed`. But what's better way to do it?
public override fun Polynomial<C>.isNotOne(): Boolean = !isOne()
public override fun Polynomial<C>.isMinusOne(): Boolean =
with(coefficients) { isNotEmpty() && asSequence().withIndex().any { (index, c) -> if (index == 0) c.isMinusOne() else c.isZero() } } // TODO: It's better to write new methods like `anyIndexed`. But what's better way to do it?
public override fun Polynomial<C>.isNotMinusOne(): Boolean = !isMinusOne()
override val zero: Polynomial<C> = Polynomial(emptyList())
override val one: Polynomial<C> = Polynomial(listOf(ring.one))
@Suppress("EXTENSION_SHADOWED_BY_MEMBER", "CovariantEquals")
public override fun Polynomial<C>.equals(other: Polynomial<C>): Boolean =
when {
this === other -> true
else -> {
if (this.degree == other.degree)
(0..degree).all { coefficients[it] == other.coefficients[it] }
else false
}
}
// endregion
// Not sure is it necessary...
// region Polynomial properties
public override val Polynomial<C>.degree: Int get() = coefficients.indexOfLast { it != ring.zero }
public override fun Polynomial<C>.asConstantOrNull(): C? =
with(coefficients) {
when {
isEmpty() -> ring.zero
degree > 0 -> null
else -> first()
}
}
public override fun Polynomial<C>.asConstant(): C = asConstantOrNull() ?: error("Can not represent non-constant polynomial as a constant")
@Suppress("NOTHING_TO_INLINE")
public inline fun Polynomial<C>.substitute(argument: C): C = this.substitute(ring, argument)
@Suppress("NOTHING_TO_INLINE")
public inline fun Polynomial<C>.substitute(argument: Polynomial<C>): Polynomial<C> = this.substitute(ring, argument)
@Suppress("NOTHING_TO_INLINE")
public inline fun Polynomial<C>.asFunction(): (C) -> C = { this.substitute(ring, it) }
@Suppress("NOTHING_TO_INLINE")
public inline fun Polynomial<C>.asFunctionOnConstants(): (C) -> C = { this.substitute(ring, it) }
@Suppress("NOTHING_TO_INLINE")
public inline fun Polynomial<C>.asFunctionOnPolynomials(): (Polynomial<C>) -> Polynomial<C> = { this.substitute(ring, it) }
/**
* Evaluates the polynomial for the given value [arg].
*/
public operator fun Polynomial<T>.invoke(arg: T): T = value(ring, arg)
public fun Polynomial<T>.asFunction(): (T) -> T = asFunction(ring)
@Suppress("NOTHING_TO_INLINE")
public inline operator fun Polynomial<C>.invoke(argument: C): C = this.substitute(ring, argument)
@Suppress("NOTHING_TO_INLINE")
public inline operator fun Polynomial<C>.invoke(argument: Polynomial<C>): Polynomial<C> = this.substitute(ring, argument)
// endregion
}
public inline fun <T, C, R> C.polynomial(block: PolynomialSpace<T, C>.() -> R): R where C : Ring<T>, C : ScaleOperations<T> {
contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) }
return PolynomialSpace(this).block()
/**
* Space of polynomials constructed over ring.
*
* @param C the type of constants. Polynomials have them as a coefficients in their terms.
* @param A type of underlying ring of constants. It's [Ring] of [C].
* @param ring underlying ring of constants of type [A].
*/
public class ScalablePolynomialSpace<C, A>(
ring: A,
) : PolynomialSpace<C, A>(ring), ScaleOperations<Polynomial<C>> where A : Ring<C>, A : ScaleOperations<C> {
override fun scale(a: Polynomial<C>, value: Double): Polynomial<C> =
ring { Polynomial(List(a.coefficients.size) { index -> a.coefficients[index] * value }) }
}

View File

@ -0,0 +1,139 @@
/*
* Copyright 2018-2021 KMath contributors.
* Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
*/
package space.kscience.kmath.functions
import space.kscience.kmath.misc.UnstableKMathAPI
import space.kscience.kmath.operations.*
import kotlin.contracts.InvocationKind
import kotlin.contracts.contract
import kotlin.jvm.JvmName
import kotlin.math.pow
// region Utilities
/**
* Removes zeros on the end of the coefficient list of polynomial.
*/
//context(PolynomialSpace<C, A>)
//fun <C, A: Ring<C>> Polynomial<C>.removeZeros() : Polynomial<C> =
// if (degree > -1) Polynomial(coefficients.subList(0, degree + 1)) else zero
/**
* Crates a [PolynomialSpace] over received ring.
*/
public fun <C, A : Ring<C>> A.polynomial(): PolynomialSpace<C, A> =
PolynomialSpace(this)
/**
* Crates a [PolynomialSpace]'s scope over received ring.
*/
public inline fun <C, A : Ring<C>, R> A.polynomial(block: PolynomialSpace<C, A>.() -> R): R {
contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) }
return PolynomialSpace(this).block()
}
/**
* Crates a [ScalablePolynomialSpace] over received scalable ring.
*/
public fun <C, A> A.scalablePolynomial(): ScalablePolynomialSpace<C, A> where A : Ring<C>, A : ScaleOperations<C> =
ScalablePolynomialSpace(this)
/**
* Crates a [ScalablePolynomialSpace]'s scope over received scalable ring.
*/
public inline fun <C, A, R> A.scalablePolynomial(block: ScalablePolynomialSpace<C, A>.() -> R): R where A : Ring<C>, A : ScaleOperations<C> {
contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) }
return ScalablePolynomialSpace(this).block()
}
// endregion
// region Polynomial substitution and functional representation
// TODO: May be apply Horner's method too?
/**
* Evaluates the value of the given double polynomial for given double argument.
*/
public fun Polynomial<Double>.substitute(arg: Double): Double =
coefficients.reduceIndexedOrNull { index, acc, c ->
acc + c * arg.pow(index)
} ?: .0
/**
* Evaluates the value of the given polynomial for given argument.
*
* It is an implementation of [Horner's method](https://en.wikipedia.org/wiki/Horner%27s_method).
*/
public fun <C> Polynomial<C>.substitute(ring: Ring<C>, arg: C): C = ring {
if (coefficients.isEmpty()) return@ring zero
var result: C = coefficients.last()
for (j in coefficients.size - 2 downTo 0) {
result = (arg * result) + coefficients[j]
}
return result
}
// TODO: (Waiting for hero) Replace with optimisation: the [result] may be unboxed, and all operations may be performed
// as soon as possible on it
public fun <C> Polynomial<C>.substitute(ring: Ring<C>, arg: Polynomial<C>) : Polynomial<C> = ring.polynomial {
if (coefficients.isEmpty()) return zero
var result: Polynomial<C> = coefficients.last().asPolynomial()
for (j in coefficients.size - 2 downTo 0) {
result = (arg * result) + coefficients[j]
}
return result
}
/**
* Represent the polynomial as a regular context-less function.
*/
public fun <C, A : Ring<C>> Polynomial<C>.asFunction(ring: A): (C) -> C = { substitute(ring, it) }
/**
* Represent the polynomial as a regular context-less function.
*/
public fun <C, A : Ring<C>> Polynomial<C>.asPolynomialFunctionOver(ring: A): (Polynomial<C>) -> Polynomial<C> = { substitute(ring, it) }
// endregion
// region Algebraic derivative and antiderivative
/**
* Returns algebraic derivative of received polynomial.
*/
@UnstableKMathAPI
public fun <C, A> Polynomial<C>.derivative(
algebra: A,
): Polynomial<C> where A : Ring<C>, A : NumericAlgebra<C> = algebra {
Polynomial(coefficients.drop(1).mapIndexed { index, t -> number(index) * t })
}
/**
* Create a polynomial witch represents indefinite integral version of this polynomial
*/
@UnstableKMathAPI
public fun <C, A> Polynomial<C>.antiderivative(
algebra: A,
): Polynomial<C> where A : Field<C>, A : NumericAlgebra<C> = algebra {
val integratedCoefficients = buildList(coefficients.size + 1) {
add(zero)
coefficients.forEachIndexed{ index, t -> add(t / (number(index) + one)) }
}
Polynomial(integratedCoefficients)
}
/**
* Compute a definite integral of a given polynomial in a [range]
*/
@UnstableKMathAPI
public fun <C : Comparable<C>> Polynomial<C>.integrate(
algebra: Field<C>,
range: ClosedRange<C>,
): C = algebra {
val integral = antiderivative(algebra)
integral.substitute(algebra, range.endInclusive) - integral.substitute(algebra, range.start)
}

View File

@ -7,6 +7,7 @@ package space.kscience.kmath.integration
import space.kscience.kmath.functions.PiecewisePolynomial
import space.kscience.kmath.functions.integrate
import space.kscience.kmath.functions.antiderivative
import space.kscience.kmath.interpolation.PolynomialInterpolator
import space.kscience.kmath.interpolation.SplineInterpolator
import space.kscience.kmath.interpolation.interpolatePolynomials
@ -23,7 +24,7 @@ import space.kscience.kmath.structures.MutableBufferFactory
@OptIn(PerformancePitfall::class)
@UnstableKMathAPI
public fun <T : Comparable<T>> PiecewisePolynomial<T>.integrate(algebra: Field<T>): PiecewisePolynomial<T> =
PiecewisePolynomial(pieces.map { it.first to it.second.integrate(algebra) })
PiecewisePolynomial(pieces.map { it.first to it.second.antiderivative(algebra) })
/**
* Compute definite integral of given [PiecewisePolynomial] piece by piece in a given [range]

View File

@ -9,7 +9,7 @@ package space.kscience.kmath.interpolation
import space.kscience.kmath.data.XYColumnarData
import space.kscience.kmath.functions.PiecewisePolynomial
import space.kscience.kmath.functions.value
import space.kscience.kmath.functions.substitute
import space.kscience.kmath.misc.UnstableKMathAPI
import space.kscience.kmath.operations.Ring
import space.kscience.kmath.structures.Buffer
@ -33,7 +33,7 @@ public interface PolynomialInterpolator<T : Comparable<T>> : Interpolator<T, T,
public fun interpolatePolynomials(points: XYColumnarData<T, T, T>): PiecewisePolynomial<T>
override fun interpolate(points: XYColumnarData<T, T, T>): (T) -> T = { x ->
interpolatePolynomials(points).value(algebra, x) ?: getDefaultValue()
interpolatePolynomials(points).substitute(algebra, x) ?: getDefaultValue()
}
}

View File

@ -5,13 +5,22 @@
package space.kscience.kmath.functions
import space.kscience.kmath.operations.algebra
import kotlin.test.Test
import kotlin.test.assertEquals
class PolynomialTest {
@Test
fun simple_polynomial_test() {
Double.algebra.scalablePolynomial {
val x = Polynomial(listOf(0.0, 1.0))
val polynomial = x * x - 2 * x + 1
assertEquals(0.0, polynomial.substitute(1.0), 0.001)
}
}
@Test
fun testIntegration() {
val polynomial = Polynomial(1.0, -2.0, 1.0)
assertEquals(0.0, polynomial.value(1.0), 0.001)
assertEquals(0.0, polynomial.substitute(1.0), 0.001)
}
}

View File

@ -274,11 +274,6 @@ argparse@^2.0.1:
resolved "https://registry.yarnpkg.com/argparse/-/argparse-2.0.1.tgz#246f50f3ca78a3240f6c997e8a9bd1eac49e4b38"
integrity sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q==
astring@1.7.5:
version "1.7.5"
resolved "https://registry.yarnpkg.com/astring/-/astring-1.7.5.tgz#a7d47fceaf32b052d33a3d07c511efeec67447ca"
integrity sha512-lobf6RWXb8c4uZ7Mdq0U12efYmpD1UFnyOWVJPTa3ukqZrMopav+2hdNu0hgBF0JIBFK9QgrBDfwYvh3DFJDAA==
balanced-match@^1.0.0:
version "1.0.2"
resolved "https://registry.yarnpkg.com/balanced-match/-/balanced-match-1.0.2.tgz#e83e3a7e3f300b34cb9d87f615fa0cbf357690ee"
@ -294,24 +289,11 @@ base64id@2.0.0, base64id@~2.0.0:
resolved "https://registry.yarnpkg.com/base64id/-/base64id-2.0.0.tgz#2770ac6bc47d312af97a8bf9a634342e0cd25cb6"
integrity sha512-lGe34o6EHj9y3Kts9R4ZYs/Gr+6N7MCaMlIFA3F1R2O5/m7K06AxfSeO5530PEERE6/WyEg3lsuyw4GHlPZHog==
benchmark@*:
version "2.1.4"
resolved "https://registry.yarnpkg.com/benchmark/-/benchmark-2.1.4.tgz#09f3de31c916425d498cc2ee565a0ebf3c2a5629"
integrity sha1-CfPeMckWQl1JjMLuVloOvzwqVik=
dependencies:
lodash "^4.17.4"
platform "^1.3.3"
binary-extensions@^2.0.0:
version "2.2.0"
resolved "https://registry.yarnpkg.com/binary-extensions/-/binary-extensions-2.2.0.tgz#75f502eeaf9ffde42fc98829645be4ea76bd9e2d"
integrity sha512-jDctJ/IVQbZoJykoeHbhXpOlNBqGNcwXJKJog42E5HDPUwQTSdjCHdihjj0DlnheQ7blbT6dHOafNAiS8ooQKA==
binaryen@101.0.0:
version "101.0.0"
resolved "https://registry.yarnpkg.com/binaryen/-/binaryen-101.0.0.tgz#42a9e4cc7a22e2c1d75a31d28005a9b518b2c555"
integrity sha512-FRmVxvrR8jtcf0qcukNAPZDM3dZ2sc9GmA/hKxBI7k3fFzREKh1cAs+ruQi+ITTKz7u/AuFMuVnbJwTh0ef/HQ==
body-parser@^1.19.0:
version "1.19.1"
resolved "https://registry.yarnpkg.com/body-parser/-/body-parser-1.19.1.tgz#1499abbaa9274af3ecc9f6f10396c995943e31d4"
@ -599,14 +581,6 @@ dom-serialize@^2.2.1:
extend "^3.0.0"
void-elements "^2.0.0"
dukat@0.5.8-rc.4:
version "0.5.8-rc.4"
resolved "https://registry.yarnpkg.com/dukat/-/dukat-0.5.8-rc.4.tgz#90384dcb50b14c26f0e99dae92b2dea44f5fce21"
integrity sha512-ZnMt6DGBjlVgK2uQamXfd7uP/AxH7RqI0BL9GLrrJb2gKdDxvJChWy+M9AQEaL+7/6TmxzJxFOsRiInY9oGWTA==
dependencies:
google-protobuf "3.12.2"
typescript "3.9.5"
ee-first@1.1.1:
version "1.1.1"
resolved "https://registry.yarnpkg.com/ee-first/-/ee-first-1.1.1.tgz#590c61156b0ae2f4f0255732a158b266bc56b21d"
@ -881,11 +855,6 @@ glob@^7.1.3, glob@^7.1.7:
once "^1.3.0"
path-is-absolute "^1.0.0"
google-protobuf@3.12.2:
version "3.12.2"
resolved "https://registry.yarnpkg.com/google-protobuf/-/google-protobuf-3.12.2.tgz#50ce9f9b6281235724eb243d6a83e969a2176e53"
integrity sha512-4CZhpuRr1d6HjlyrxoXoocoGFnRYgKULgMtikMddA9ztRyYR59Aondv2FioyxWVamRo0rF2XpYawkTCBEQOSkA==
graceful-fs@^4.1.2, graceful-fs@^4.1.6, graceful-fs@^4.2.0, graceful-fs@^4.2.4, graceful-fs@^4.2.6:
version "4.2.9"
resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.2.9.tgz#041b05df45755e587a24942279b9d113146e1c96"
@ -1065,11 +1034,6 @@ jest-worker@^27.4.1:
merge-stream "^2.0.0"
supports-color "^8.0.0"
js-base64@3.6.1:
version "3.6.1"
resolved "https://registry.yarnpkg.com/js-base64/-/js-base64-3.6.1.tgz#555aae398b74694b4037af1f8a5a6209d170efbe"
integrity sha512-Frdq2+tRRGLQUIQOgsIGSCd1VePCS2fsddTG5dTCqR0JHgltXWfsxnY0gIXPoMeRmdom6Oyq+UMOFg5suduOjQ==
js-yaml@4.1.0:
version "4.1.0"
resolved "https://registry.yarnpkg.com/js-yaml/-/js-yaml-4.1.0.tgz#c1fb65f8f5017901cdd2c951864ba18458a10602"
@ -1179,7 +1143,7 @@ locate-path@^6.0.0:
dependencies:
p-locate "^5.0.0"
lodash@^4.17.15, lodash@^4.17.21, lodash@^4.17.4:
lodash@^4.17.15, lodash@^4.17.21:
version "4.17.21"
resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz#679591c564c3bffaae8454cf0b3df370c3d6911c"
integrity sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg==
@ -1437,11 +1401,6 @@ pkg-dir@^4.2.0:
dependencies:
find-up "^4.0.0"
platform@^1.3.3:
version "1.3.6"
resolved "https://registry.yarnpkg.com/platform/-/platform-1.3.6.tgz#48b4ce983164b209c2d45a107adb31f473a6e7a7"
integrity sha512-fnWVljUchTro6RiCFvCXBbNhJc2NijN7oIQxbwsyL0buWJPG85v81ehlHI9fXrJsMNgTofEoWIQeClKpgxFLrg==
postcss-modules-extract-imports@^3.0.0:
version "3.0.0"
resolved "https://registry.yarnpkg.com/postcss-modules-extract-imports/-/postcss-modules-extract-imports-3.0.0.tgz#cda1f047c0ae80c97dbe28c3e76a43b88025741d"
@ -1696,14 +1655,6 @@ source-map-loader@3.0.0:
iconv-lite "^0.6.2"
source-map-js "^0.6.2"
source-map-support@0.5.20:
version "0.5.20"
resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.5.20.tgz#12166089f8f5e5e8c56926b377633392dd2cb6c9"
integrity sha512-n1lZZ8Ve4ksRqizaBQgxXDgKwttHDhyfQjA6YZZn8+AroHbsIz+JjwxQDxbp+7y5OYCI8t1Yk7etjD9CRd2hIw==
dependencies:
buffer-from "^1.0.0"
source-map "^0.6.0"
source-map-support@~0.5.20:
version "0.5.21"
resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.5.21.tgz#04fe7c7f9e1ed2d662233c28cb2b35b9f63f6e4f"
@ -1838,11 +1789,6 @@ type-is@~1.6.18:
media-typer "0.3.0"
mime-types "~2.1.24"
typescript@3.9.5:
version "3.9.5"
resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.9.5.tgz#586f0dba300cde8be52dd1ac4f7e1009c1b13f36"
integrity sha512-hSAifV3k+i6lEoCJ2k6R2Z/rp/H3+8sdmcn5NrS3/3kE7+RyZXm9aqvxWqjEXHAd8b0pShatpcdMTvEdvAJltQ==
ua-parser-js@^0.7.28:
version "0.7.31"
resolved "https://registry.yarnpkg.com/ua-parser-js/-/ua-parser-js-0.7.31.tgz#649a656b191dffab4f21d5e053e27ca17cbff5c6"