1 files changed, 2 insertions, 1 deletions
diff --git a/fir_window_vonhann.awk b/fir_window_vonhann.awk
index 3c831c7..d4b010e 100644
--- a/fir_window_vonhann.awk
+++ b/fir_window_vonhann.awk
@@ -1,6 +1,7 @@
 #!/usr/bin/awk -f
 
 ### fir_window_vonhann.awk
+# generate a vonHann raised cosine FIR window
 # https://en.wikipedia.org/wiki/Window_function provides a few values for the
 # 'a0' and 'a1' parameters of the raised cosine.
 
@@ -20,7 +21,7 @@ BEGIN {
 
     # window interval goes from -M to M
     M = 0.5*(N - 1)
-    pi = 4*atan2(1,1)
+    pi = 4.0*atan2(1.0, 1.0)
 
     for (n=-M; n<=M; n++) {
         if (N > 1 && M > 0) {