diff --git a/src/c/funktionen.h b/src/c/funktionen.h
index 02a0618..b6e14ed 100644
--- a/src/c/funktionen.h
+++ b/src/c/funktionen.h
@@ -50,4 +50,7 @@ float arcSine(float x);
 // Function to calculate the arc cosine of a value and return the result in radians
 float arcCosine(float x);
 
+// Function to calculate the arc tangent of a value and return the result in radians
+float arcTangent(float x);
+
 #endif
\ No newline at end of file