Merge commit 'refs/pull/322/head' of ssh://git.jetbrains.space/mipt-npm/sci/kmath into feature/tensor-algebra

kmath-tensors/src/commonMain/kotlin/space/kscience/kmath/tensors/core/tensorCasts.kt

@@ -35,3 +35,35 @@ public fun IntTensor.toIntArray(): IntArray {
         mutableBuffer[bufferStart + i]
     }
 }
+
+/**
+ * Casts [Array<DoubleArray>] to [DoubleTensor]
+ */
+public fun Array<DoubleArray>.toDoubleTensor(): DoubleTensor {
+    val n = size
+    check(n > 0) { "An empty array cannot be casted to tensor" }
+    val m = first().size
+    check(m > 0) { "Inner arrays must have at least 1 argument" }
+    check(all { size == m }) { "Inner arrays must be the same size" }
+
+    val shape = intArrayOf(n, m)
+    val buffer = this.flatMap { arr -> arr.map { it } }.toDoubleArray()
+
+    return DoubleTensor(shape, buffer, 0)
+}
+
+/**
+ * Casts [Array<IntArray>] to [IntTensor]
+ */
+public fun Array<IntArray>.toIntTensor(): IntTensor {
+    val n = size
+    check(n > 0) { "An empty array cannot be casted to tensor" }
+    val m = first().size
+    check(m > 0) { "Inner arrays must have at least 1 argument" }
+    check(all { size == m }) { "Inner arrays must be the same size" }
+
+    val shape = intArrayOf(n, m)
+    val buffer = this.flatMap { arr -> arr.map { it } }.toIntArray()
+
+    return IntTensor(shape, buffer, 0)
+}