From fd4108b74fbd012796fa12f913675ed55d8eae62 Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Mon, 19 Apr 2021 11:26:06 +0300
Subject: [PATCH] fix segmented integral

---
 .../space/kscience/kmath/integration/GaussIntegrator.kt       | 2 +-
 .../space/kscience/kmath/integration/GaussIntegralTest.kt     | 4 ++--
 .../kotlin/space/kscience/kmath/nd4j/Nd4jArrayStructure.kt    | 3 +--
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/kmath-functions/src/commonMain/kotlin/space/kscience/kmath/integration/GaussIntegrator.kt b/kmath-functions/src/commonMain/kotlin/space/kscience/kmath/integration/GaussIntegrator.kt
index 749f3cc72..ae82a40be 100644
--- a/kmath-functions/src/commonMain/kotlin/space/kscience/kmath/integration/GaussIntegrator.kt
+++ b/kmath-functions/src/commonMain/kotlin/space/kscience/kmath/integration/GaussIntegrator.kt
@@ -102,7 +102,7 @@ public fun <T : Any> Field<T>.integrate(
     require(intervals > 0) { "Number of intervals must be positive" }
     val rangeSize = (range.endInclusive - range.start) / intervals
     val ranges = UnivariateIntegrandRanges(
-        (0 until intervals).map { i -> (rangeSize * i)..(rangeSize * i + 1) to order }
+        (0 until intervals).map { i -> (rangeSize * i)..(rangeSize * (i + 1)) to order }
     )
     return GaussIntegrator(this).integrate(
         UnivariateIntegrand(
diff --git a/kmath-functions/src/commonTest/kotlin/space/kscience/kmath/integration/GaussIntegralTest.kt b/kmath-functions/src/commonTest/kotlin/space/kscience/kmath/integration/GaussIntegralTest.kt
index 509821e61..195711452 100644
--- a/kmath-functions/src/commonTest/kotlin/space/kscience/kmath/integration/GaussIntegralTest.kt
+++ b/kmath-functions/src/commonTest/kotlin/space/kscience/kmath/integration/GaussIntegralTest.kt
@@ -24,14 +24,14 @@ class GaussIntegralTest {
 
     @Test
     fun gaussUniform() {
-        val res = DoubleField.integrate(0.0..100.0,300) { x ->
+        val res = DoubleField.integrate(0.0..100.0) { x ->
             if(x in 30.0..50.0){
                 1.0
             } else {
                 0.0
             }
         }
-        assertEquals(20.0, res.value!!, 1.0)
+        assertEquals(20.0, res.value!!, 0.5)
     }
 
 
diff --git a/kmath-nd4j/src/main/kotlin/space/kscience/kmath/nd4j/Nd4jArrayStructure.kt b/kmath-nd4j/src/main/kotlin/space/kscience/kmath/nd4j/Nd4jArrayStructure.kt
index b9aa251d2..79db86fcc 100644
--- a/kmath-nd4j/src/main/kotlin/space/kscience/kmath/nd4j/Nd4jArrayStructure.kt
+++ b/kmath-nd4j/src/main/kotlin/space/kscience/kmath/nd4j/Nd4jArrayStructure.kt
@@ -20,8 +20,7 @@ public sealed class Nd4jArrayStructure<T> : MutableStructureND<T> {
      */
     public abstract val ndArray: INDArray
 
-    public override val shape: IntArray
-        get() = ndArray.shape().toIntArray()
+    public override val shape: IntArray get() = ndArray.shape().toIntArray()
 
     internal abstract fun elementsIterator(): Iterator<Pair<IntArray, T>>
     internal fun indicesIterator(): Iterator<IntArray> = ndArray.indicesIterator()