diff --git a/src/c/funktionen.h b/src/c/funktionen.h
index 037ed94..fa73c03 100644
--- a/src/c/funktionen.h
+++ b/src/c/funktionen.h
@@ -16,4 +16,7 @@ float cubeRoot(float x);
 // Function to calculate the absolute value of a number
 float absolute(float x);
 
+// Function to calculate the logarithm (base 10) of a number
+float logarithm(float x);
+
 #endif
\ No newline at end of file