Safe item method and view_as added

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

@@ -14,9 +14,13 @@ public class RealTensor(
         TensorStrides(shape),
         RealBuffer(buffer)
     ) {
-    override fun item(): Double = buffer[0]
+    override fun item(): Double {
+        check(buffer.size > 0) { "The tensor is empty" }
+        return buffer[0]
+    }
 }
 
+
 public class RealTensorAlgebra : TensorPartialDivisionAlgebra<Double, RealTensor> {
 
     override fun Double.plus(other: RealTensor): RealTensor {
@@ -116,6 +120,10 @@ public class RealTensorAlgebra : TensorPartialDivisionAlgebra<Double, RealTensor
         TODO("Not yet implemented")
     }
 
+    override fun RealTensor.view_as(other: RealTensor): RealTensor {
+        TODO("Not yet implemented")
+    }
+
     override fun RealTensor.abs(): RealTensor {
         TODO("Not yet implemented")
     }

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

@@ -40,6 +40,7 @@ public interface TensorAlgebra<T, TensorType : TensorStructure<T>>{
 
     //https://pytorch.org/docs/stable/tensor_view.html
     public fun TensorType.view(shape: IntArray): TensorType
+    public fun TensorType.view_as(other: TensorType): TensorType
 
     //https://pytorch.org/docs/stable/generated/torch.abs.html
     public fun TensorType.abs(): TensorType