diff --git a/src/main/java/de/neemann/digital/draw/graphics/GraphicSwing.java b/src/main/java/de/neemann/digital/draw/graphics/GraphicSwing.java
index 0c4fc6609..9bf48ce61 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/GraphicSwing.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/GraphicSwing.java
@@ -145,9 +145,9 @@ public class GraphicSwing extends Graphic {
 
     static int getMirrorYOrientation(Orientation orientation, VectorInterface p1, VectorInterface p2, VectorInterface p3) {
         int oy = orientation.getY();
-        VectorInterface d0 = p2.sub(p1).toFloat().getOrthogonal();
+        VectorInterface d0 = p2.sub(p1).getOrthogonal();
         VectorInterface d1 = p3.sub(p1);
-        if (d1.getX() * d0.getX() + d1.getY() * d0.getY() < 0) oy = 2 - oy;
+        if (d0.scalar(d1) < 0) oy = 2 - oy;
         return oy;
     }
 
diff --git a/src/main/java/de/neemann/digital/draw/graphics/Vector.java b/src/main/java/de/neemann/digital/draw/graphics/Vector.java
index 98fcbe89d..f7af05321 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/Vector.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/Vector.java
@@ -256,4 +256,10 @@ public class Vector implements VectorInterface {
     public VectorFloat toFloat() {
         return new VectorFloat(x, y);
     }
+
+    @Override
+    public Vector getOrthogonal() {
+        return new Vector(y, -x);
+    }
+
 }
diff --git a/src/main/java/de/neemann/digital/draw/graphics/VectorFloat.java b/src/main/java/de/neemann/digital/draw/graphics/VectorFloat.java
index cd583a770..28d3ffcf2 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/VectorFloat.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/VectorFloat.java
@@ -164,11 +164,7 @@ public class VectorFloat implements VectorInterface {
         return this;
     }
 
-    /**
-     * Creates vector which is orthogonal to this one.
-     *
-     * @return the orthogonal vector
-     */
+    @Override
     public VectorFloat getOrthogonal() {
         return new VectorFloat(y, -x);
     }
diff --git a/src/main/java/de/neemann/digital/draw/graphics/VectorInterface.java b/src/main/java/de/neemann/digital/draw/graphics/VectorInterface.java
index 7b78cfd60..6d4a45dad 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/VectorInterface.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/VectorInterface.java
@@ -91,4 +91,17 @@ public interface VectorInterface {
      * @return the length of the vector
      */
     float len();
+
+    /**
+     * @return a vector which is orthogonal to this one
+     */
+    VectorInterface getOrthogonal();
+
+    /**
+     * @return the scalar product
+     */
+    default float scalar(VectorInterface v) {
+        return getXFloat() * v.getXFloat() + getYFloat() * v.getYFloat();
+    }
+
 }