diff --git a/kmath-viktor/src/main/kotlin/scientifik/kmath/viktor/ViktorNDStructure.kt b/kmath-viktor/src/main/kotlin/scientifik/kmath/viktor/ViktorNDStructure.kt
index b8cf688f4..9654ba283 100644
--- a/kmath-viktor/src/main/kotlin/scientifik/kmath/viktor/ViktorNDStructure.kt
+++ b/kmath-viktor/src/main/kotlin/scientifik/kmath/viktor/ViktorNDStructure.kt
@@ -69,9 +69,14 @@ class ViktorNDField(override val shape: IntArray) : NDField<Double, RealField, V
         return (a.f64Buffer + b.f64Buffer).asStructure()
     }
 
-//    override inline fun ViktorNDStructure.plus(b: ViktorNDStructure): ViktorNDStructure {
-//        return (f64Buffer + b.f64Buffer).asStructure()
-//    }
+    override inline fun ViktorNDStructure.plus(b: ViktorNDStructure): ViktorNDStructure {
+        return (f64Buffer + b.f64Buffer).asStructure()
+    }
+
+    override inline fun ViktorNDStructure.minus(b: ViktorNDStructure): ViktorNDStructure {
+        return (f64Buffer - b.f64Buffer).asStructure()
+    }
+
 
     override fun multiply(a: ViktorNDStructure, k: Number): ViktorNDStructure {
         return (a.f64Buffer * k.toDouble()).asStructure()