From bc4eb95ae7c05ff957092586d8823d6064dfc21f Mon Sep 17 00:00:00 2001
From: Iaroslav Postovalov <postovalovya@gmail.com>
Date: Fri, 30 Oct 2020 16:40:43 +0700
Subject: [PATCH] Add extension functions for DifferentiableMstExpression

---
 .../kotlin/kscience/kmath/ast/KotlingradSupport.kt     |  3 ++-
 .../kmath/kotlingrad/DifferentiableMstExpression.kt    | 10 ++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/examples/src/main/kotlin/kscience/kmath/ast/KotlingradSupport.kt b/examples/src/main/kotlin/kscience/kmath/ast/KotlingradSupport.kt
index 7b5e1565d..9b34426f7 100644
--- a/examples/src/main/kotlin/kscience/kmath/ast/KotlingradSupport.kt
+++ b/examples/src/main/kotlin/kscience/kmath/ast/KotlingradSupport.kt
@@ -4,6 +4,7 @@ import kscience.kmath.asm.compile
 import kscience.kmath.expressions.invoke
 import kscience.kmath.expressions.symbol
 import kscience.kmath.kotlingrad.DifferentiableMstExpression
+import kscience.kmath.kotlingrad.derivative
 import kscience.kmath.operations.RealField
 
 /**
@@ -14,7 +15,7 @@ fun main() {
     val x by symbol
 
     val actualDerivative = DifferentiableMstExpression(RealField, "x^2-4*x-44".parseMath())
-        .derivativeOrNull(listOf(x))
+        .derivative(x)
         .compile()
 
     val expectedDerivative = MstExpression(RealField, "2*x-4".parseMath()).compile()
diff --git a/kmath-kotlingrad/src/main/kotlin/kscience/kmath/kotlingrad/DifferentiableMstExpression.kt b/kmath-kotlingrad/src/main/kotlin/kscience/kmath/kotlingrad/DifferentiableMstExpression.kt
index 88cc20639..ddfc7cccb 100644
--- a/kmath-kotlingrad/src/main/kotlin/kscience/kmath/kotlingrad/DifferentiableMstExpression.kt
+++ b/kmath-kotlingrad/src/main/kotlin/kscience/kmath/kotlingrad/DifferentiableMstExpression.kt
@@ -5,6 +5,7 @@ import kscience.kmath.ast.MST
 import kscience.kmath.ast.MstAlgebra
 import kscience.kmath.ast.MstExpression
 import kscience.kmath.expressions.DifferentiableExpression
+import kscience.kmath.expressions.StringSymbol
 import kscience.kmath.expressions.Symbol
 import kscience.kmath.operations.NumericAlgebra
 
@@ -46,6 +47,15 @@ public inline class DifferentiableMstExpression<T, A>(public val expr: MstExpres
     )
 }
 
+public fun <T : Number, A : NumericAlgebra<T>> DifferentiableMstExpression<T, A>.derivative(symbols: List<Symbol>): MstExpression<T, A> =
+    derivativeOrNull(symbols)
+
+public fun <T : Number, A : NumericAlgebra<T>> DifferentiableMstExpression<T, A>.derivative(vararg symbols: Symbol): MstExpression<T, A> =
+    derivative(symbols.toList())
+
+public fun <T : Number, A : NumericAlgebra<T>> DifferentiableMstExpression<T, A>.derivative(name: String): MstExpression<T, A> =
+    derivative(StringSymbol(name))
+
 /**
  * Wraps this [MstExpression] into [DifferentiableMstExpression].
  */