From 5610302c77c4bf88a8dc7e4adbf799bdff23e47c Mon Sep 17 00:00:00 2001
From: Gerald Fournier <>
Date: Mon, 16 Feb 2026 01:59:00 +0200
Subject: [PATCH] Fix nyquist bin normalization

---
 src/frontend/com_fft.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/frontend/com_fft.c b/src/frontend/com_fft.c
index df73946a7..797fe3b63 100644
--- a/src/frontend/com_fft.c
+++ b/src/frontend/com_fft.c
@@ -189,6 +189,12 @@ com_fft(wordlist *wl)
             fdvec[i][j].cx_imag = out[j][1]/scale;
         }
 
+        /* for even-length input, the nyquist bin is paired with itself
+           and normalization does not require a factor of 2  */
+        if ( length % 2 == 0) {
+            fdvec[i][fpts-1].cx_real /= 2;
+            fdvec[i][fpts-1].cx_imag /= 2;
+        }
     }
 
     fftw_destroy_plan(plan_forward);