From e76d8e0774c2e3fe4a194e81403790d2850f4193 Mon Sep 17 00:00:00 2001
From: Alexander Nozik <altavir@gmail.com>
Date: Wed, 12 Apr 2023 11:40:27 +0300
Subject: [PATCH] fix zipWithNextCircular on single element

---
 .../kotlin/space/kscience/kmath/misc/collections.kt           | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/misc/collections.kt b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/misc/collections.kt
index afa76d2a9..f630055fa 100644
--- a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/misc/collections.kt
+++ b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/misc/collections.kt
@@ -9,7 +9,7 @@ package space.kscience.kmath.misc
  * The same as [zipWithNext], but includes link between last and first element
  */
 public inline fun <T, R> List<T>.zipWithNextCircular(transform: (a: T, b: T) -> R): List<R> {
-    if (isEmpty()) return emptyList()
+    if (size < 2) return emptyList()
     return indices.map { i ->
         if (i == size - 1) {
             transform(last(), first())
@@ -19,4 +19,4 @@ public inline fun <T, R> List<T>.zipWithNextCircular(transform: (a: T, b: T) ->
     }
 }
 
-public fun <T> List<T>.zipWithNextCircular(): List<Pair<T,T>> = zipWithNextCircular { l, r -> l to r  }
\ No newline at end of file
+public fun <T> List<T>.zipWithNextCircular(): List<Pair<T, T>> = zipWithNextCircular { l, r -> l to r }
\ No newline at end of file