diff --git a/src/reihen.c b/src/reihen.c
index 01fd0a5..b9f15e9 100644
--- a/src/reihen.c
+++ b/src/reihen.c
@@ -24,4 +24,8 @@ double exponential(double x){
         sum += (1.0/fac(i)*(powerD(i,x)));
     }
     return sum;
+}
+
+double euler(){
+    return exponential(1);
 }
\ No newline at end of file
diff --git a/src/reihen.h b/src/reihen.h
index bd4e520..20f8a18 100644
--- a/src/reihen.h
+++ b/src/reihen.h
@@ -2,5 +2,6 @@
 #define REIHEN_H
 
 double exponential(double x);
+double euler();
 
 #endif // reihen.h
\ No newline at end of file