kmath-core/src/commonMain/kotlin/space/kscience/kmath/nd/ShapeIndices.kt

@@ -51,10 +51,15 @@ public abstract class Strides : ShapeIndexer {
      */
     internal abstract val strides: IntArray
 
-    public override fun offset(index: IntArray): Int = index.mapIndexed { i, value ->
+    public override fun offset(index: IntArray): Int {
+        var res = 0
+        index.forEachIndexed { i, value ->
             if (value !in 0 until shape[i]) throw IndexOutOfBoundsException("Index $value out of shape bounds: (0, ${this.shape[i]})")
-        value * strides[i]
+            res += value * strides[i]
-    }.sum()
+
+        }
+        return res
+    }
 
     // TODO introduce a fast way to calculate index of the next element?
 
@@ -74,8 +79,7 @@ public class ColumnStrides(override val shape: ShapeND) : Strides() {
     /**
      * Strides for memory access
      */
-    override val strides: IntArray by lazy {
+    override val strides: IntArray = sequence {
-        sequence {
         var current = 1
         yield(1)
 
@@ -84,7 +88,6 @@ public class ColumnStrides(override val shape: ShapeND) : Strides() {
             yield(current)
         }
     }.toList().toIntArray()
-    }
 
     override fun index(offset: Int): IntArray {
         val res = IntArray(shape.size)
@@ -120,10 +123,10 @@ public class ColumnStrides(override val shape: ShapeND) : Strides() {
  */
 public class RowStrides(override val shape: ShapeND) : Strides() {
 
-    override val strides: IntArray by lazy {
+    override val strides: IntArray = run {
         val nDim = shape.size
         val res = IntArray(nDim)
-        if (nDim == 0) return@lazy res
+        if (nDim == 0) return@run res
 
         var current = nDim - 1
         res[current] = 1