Documentation in progress.

This commit is contained in:
Alexander Nozik 2019-02-13 14:55:44 +03:00
parent b5dd864556
commit 123e0176b8
13 changed files with 71 additions and 41 deletions

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@ -22,8 +22,8 @@ plugins {
}
allprojects {
apply(plugin = "maven-publish")
if(project.name.startsWith("kmath")) {
if (project.name.startsWith("kmath")) {
apply(plugin = "maven-publish")
apply(plugin = "com.jfrog.artifactory")
}

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@ -0,0 +1 @@
**TODO**

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@ -0,0 +1,26 @@
# Expressions
**Experimental: this API is in early stage and could change any time**
Expressions is an experimental feature which allows to construct lazily or immediately calculated parametric mathematical
expressions.
The potential use-cases for it (so far) are following:
* Lazy evaluation (in general simple lambda is better, but there are some border cases)
* Automatic differentiation in single-dimension and in multiple dimensions
* Generation of mathematical syntax trees with subsequent code generation for other languages
* Maybe symbolic computations (needs additional research)
The workhorse of this API is `Expression` interface which exposes single `operator fun invoke(arguments: Map<String, T>): T`
method. `ExpressionContext` is used to generate expressions and introduce variables.
Currently there are two implementations:
* Generic `ExpressionField` in `kmath-core` which allows construction of custom lazy expressions
* Auto-differentiation expression in `kmath-commons` module allows to use full power of `DerivativeStructure`
from commons-math. **TODO: add example**

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**TODO**

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@ -14,7 +14,7 @@ val c3 = c1 + c2
`ComplexField` also features special operations to mix complex and real numbers, for example:
```kotlin
val c1 = Complex(1.0,2.0)
val c1 = Complex(1.0, 2.0)
val c2 = ComplexField.run{ c1 - 1.0} // Returns: [re:0.0, im: 2.0]
val c3 = ComplexField.run{ c1 - i*2.0}
```
@ -27,8 +27,8 @@ that. Watch [KT-10468](https://youtrack.jetbrains.com/issue/KT-10468) and [KEEP-
Contexts allow one to build more complex structures. For example, it is possible to create a `Matrix` from complex elements like so:
```kotlin
val element = NDElements.create(field = ComplexField, shape = intArrayOf(2,2)){index: IntArray ->
Complex(index[0] - index[1], index[0] + index[1])
val element = NDElement.complex(shape = intArrayOf(2,2)){ index: IntArray ->
Complex(index[0].toDouble() - index[1].toDouble(), index[0].toDouble() + index[1].toDouble())
}
```

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@ -1,15 +0,0 @@
plugins {
kotlin("jvm")
}
description = "Examples for different kmath features"
dependencies {
implementation(project(":kmath-core"))
implementation(project(":kmath-coroutines"))
implementation(project(":kmath-commons"))
implementation(project(":kmath-koma"))
implementation(group = "com.kyonifer", name = "koma-core-ejml", version = "0.12")
testImplementation("org.jetbrains.kotlin:kotlin-test")
testImplementation("org.jetbrains.kotlin:kotlin-test-junit")
}

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@ -0,0 +1 @@
@file:DependsOn("scientifik:kmath-core-jvm:0.0.3-dev")

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@ -2,6 +2,7 @@ package scientifik.kmath.expressions
import org.apache.commons.math3.analysis.differentiation.DerivativeStructure
import scientifik.kmath.operations.ExtendedField
import scientifik.kmath.operations.Field
import kotlin.properties.ReadOnlyProperty
import kotlin.reflect.KProperty
@ -25,8 +26,8 @@ class DerivativeStructureField(val order: Int, val parameters: Map<String, Doubl
}
}
fun variable(name: String): DerivativeStructure =
variables[name] ?: error("A variable with name ${name} does not exist")
fun variable(name: String, default: DerivativeStructure? = null): DerivativeStructure =
variables[name] ?: default ?: error("A variable with name $name does not exist")
fun Number.const() = DerivativeStructure(order, parameters.size, toDouble())
@ -102,5 +103,26 @@ class DiffExpression(val function: DerivativeStructureField.() -> DerivativeStru
fun DiffExpression.derivative(vararg orders: Pair<String, Int>) = derivative(mapOf(*orders))
fun DiffExpression.derivative(name: String) = derivative(name to 1)
/**
* A context for [DiffExpression] (not to be confused with [DerivativeStructure])
*/
object DiffExpressionContext : ExpressionContext<Double>, Field<DiffExpression> {
override fun variable(name: String, default: Double?) = DiffExpression { variable(name, default?.const()) }
override fun const(value: Double): DiffExpression = DiffExpression { value.const() }
override fun add(a: DiffExpression, b: DiffExpression) = DiffExpression { a.function(this) + b.function(this) }
override val zero = DiffExpression { 0.0.const() }
override fun multiply(a: DiffExpression, k: Number) = DiffExpression { a.function(this) * k }
override val one = DiffExpression { 1.0.const() }
override fun multiply(a: DiffExpression, b: DiffExpression) = DiffExpression { a.function(this) * b.function(this) }
override fun divide(a: DiffExpression, b: DiffExpression) = DiffExpression { a.function(this) / b.function(this) }
}

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@ -4,16 +4,27 @@ import scientifik.kmath.operations.Field
import scientifik.kmath.operations.Ring
import scientifik.kmath.operations.Space
/**
* An elementary function that could be invoked on a map of arguments
*/
interface Expression<T> {
operator fun invoke(arguments: Map<String, T>): T
}
operator fun <T> Expression<T>.invoke(vararg pairs: Pair<String, T>): T = invoke(mapOf(*pairs))
/**
* A context for expression construction
*/
interface ExpressionContext<T> {
/**
* Introduce a variable into expression context
*/
fun variable(name: String, default: T? = null): Expression<T>
/**
* A constant expression which does not depend on arguments
*/
fun const(value: T): Expression<T>
}

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@ -1,16 +0,0 @@
package scientifik.kmath.structures
class LazyNDFieldTest {
// @Test
// fun testLazyStructure() {
// var counter = 0
// val regularStructure = NDField.auto(intArrayOf(2, 2, 2), IntRing).produce { it[0] + it[1] - it[2] }
// val result = (regularStructure.lazy(IntRing) + 2).map {
// counter++
// it * it
// }
// assertEquals(4, result[0, 0, 0])
// assertEquals(1, counter)
// }
}

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@ -25,6 +25,5 @@ include(
":kmath-commons",
":kmath-koma",
":kmath-sequential",
":benchmarks",
":examples"
":benchmarks"
)