From e14342e827e2b42e43c006df90c7ad99e5124b3c Mon Sep 17 00:00:00 2001
From: wukong <wukong@longaeva>
Date: Sun, 4 Nov 2018 10:59:44 -0800
Subject: added gaussian.awk based on hamming script; added pwr(x,p) function
 to sterling_approx; minor clean up all around;

---
 hamming.awk | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

(limited to 'hamming.awk')

diff --git a/hamming.awk b/hamming.awk
index 95f1cde..fd6d89c 100644
--- a/hamming.awk
+++ b/hamming.awk
@@ -6,25 +6,34 @@
 # 'a0' and 'a1' parameters of the raised cosine.
 
 BEGIN {
+
+    ### R.W. Hamming, "Digital Filters"
+    # H = "0.23 0.54 0.23"
+
     N = ARGV[1]
-    pi = 4*(4*atan2(1,5) - atan2(1,239))
+    # window interval goes from -M to M
+    M = 0.5*(N - 1)
+    pi = 4*atan2(1,1)
 
-    #a0 = (25.0/46.0)
-    #a1 = (21.0/46.0)
+    a0 = (25.0/46.0)
+    a1 = (21.0/46.0)
 
     ### optimal values for equal-ripple
-    a0 = 0.53836
-    a1 = 0.46164
+    #a0 = 0.53836
+    #a1 = 0.46164
 
-    ### R.W. Hamming, "Digital Filters"
-    # H = "0.23 0.54 0.23"
+    ### VonHann
+    #a0 = 0.5
+    #a1 = 0.5
 
-    for (n=0; n<N; n++) {
-        if (N > 1) {
-            w[n] = a0 - a1*cos((2*pi*n)/(N - 1))
-            sum_w += w[n]
+    for (n=-M; n<=M; n++) {
+        if (N > 1 && M > 0) {
+            w[n] = a0 + a1*cos((pi*n)/M)
+            print n, w[n]/M
+        }
+        else {
+            print n, 1.0
         }
-        print 2.0*(w[n])/(N + 1)
     }
 
 }
-- 
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