From 86a45504e37d93be835e2d31da15a61acc074160 Mon Sep 17 00:00:00 2001
From: Iaroslav Postovalov <postovalovya@gmail.com>
Date: Thu, 10 Jun 2021 01:02:57 +0700
Subject: [PATCH] Add contentEquals extension to ND algebra and LinearSpace

---
 .../kscience/kmath/linear/LinearSpace.kt      |  2 +-
 .../space/kscience/kmath/nd/StructureND.kt    | 41 +++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/linear/LinearSpace.kt b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/linear/LinearSpace.kt
index 63b881105..fdb5c2090 100644
--- a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/linear/LinearSpace.kt
+++ b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/linear/LinearSpace.kt
@@ -29,7 +29,7 @@ public typealias MutableMatrix<T> = MutableStructure2D<T>
 public typealias Point<T> = Buffer<T>
 
 /**
- * Basic operations on matrices and vectors. Operates on [Matrix].
+ * Basic operations on matrices and vectors.
  *
  * @param T the type of items in the matrices.
  * @param A the type of ring over [T].
diff --git a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/nd/StructureND.kt b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/nd/StructureND.kt
index 716bd15f3..cfb20f441 100644
--- a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/nd/StructureND.kt
+++ b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/nd/StructureND.kt
@@ -5,8 +5,11 @@
 
 package space.kscience.kmath.nd
 
+import space.kscience.kmath.linear.LinearSpace
 import space.kscience.kmath.misc.PerformancePitfall
 import space.kscience.kmath.misc.UnstableKMathAPI
+import space.kscience.kmath.operations.Ring
+import space.kscience.kmath.operations.invoke
 import space.kscience.kmath.structures.Buffer
 import space.kscience.kmath.structures.BufferFactory
 import kotlin.jvm.JvmName
@@ -145,6 +148,44 @@ public interface StructureND<out T> {
     }
 }
 
+/**
+ * Indicates whether some [StructureND] is equal to another one.
+ */
+@PerformancePitfall
+public fun <T : Comparable<T>> AlgebraND<T, Ring<T>>.contentEquals(
+    st1: StructureND<T>,
+    st2: StructureND<T>,
+): Boolean = StructureND.contentEquals(st1, st2)
+
+/**
+ * Indicates whether some [StructureND] is equal to another one.
+ */
+@PerformancePitfall
+public fun <T : Comparable<T>> LinearSpace<T, Ring<T>>.contentEquals(
+    st1: StructureND<T>,
+    st2: StructureND<T>,
+): Boolean = StructureND.contentEquals(st1, st2)
+
+/**
+ * Indicates whether some [StructureND] is equal to another one with [absoluteTolerance].
+ */
+@PerformancePitfall
+public fun <T : Comparable<T>> GroupND<T, Ring<T>>.contentEquals(
+    st1: StructureND<T>,
+    st2: StructureND<T>,
+    absoluteTolerance: T,
+): Boolean = st1.elements().all { (index, value) -> elementContext { (value - st2[index]) } < absoluteTolerance }
+
+/**
+ * Indicates whether some [StructureND] is equal to another one with [absoluteTolerance].
+ */
+@PerformancePitfall
+public fun <T : Comparable<T>> LinearSpace<T, Ring<T>>.contentEquals(
+    st1: StructureND<T>,
+    st2: StructureND<T>,
+    absoluteTolerance: T,
+): Boolean = st1.elements().all { (index, value) -> elementAlgebra { (value - st2[index]) } < absoluteTolerance }
+
 /**
  * Returns the value at the specified indices.
  *