From 5e82b63f6218e7deb038088f8c04bc84334241c4 Mon Sep 17 00:00:00 2001
From: dwarning <dietmar.warning@gmail.com>
Date: Sun, 1 Mar 2026 16:14:04 +0100
Subject: [PATCH] adapt FFT point number for real input vectors in fft cmd and
 vector operation wrt. bug #829

---
 src/frontend/com_fft.c    | 2 +-
 src/maths/cmaths/cmath4.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/frontend/com_fft.c b/src/frontend/com_fft.c
index 2d592525b..baefb2c51 100644
--- a/src/frontend/com_fft.c
+++ b/src/frontend/com_fft.c
@@ -167,7 +167,7 @@ com_fft(wordlist *wl)
         in[j] = tdvec[0][j]*win[j];
 
     /* data have same type and length - so we need only one plan */
-    plan_forward = fftw_plan_dft_r2c_1d(length, in, out, FFTW_ESTIMATE); 
+    plan_forward = fftw_plan_dft_r2c_1d(length-1, in, out, FFTW_ESTIMATE); 
 
     for (i = 0; i<ngood; i++) {
 
diff --git a/src/maths/cmaths/cmath4.c b/src/maths/cmaths/cmath4.c
index a1f547d97..c29e53634 100644
--- a/src/maths/cmaths/cmath4.c
+++ b/src/maths/cmaths/cmath4.c
@@ -770,7 +770,7 @@ cx_fft(void *data, short int type, int length, int *newlength, short int *newtyp
         for (i = 0; i < length; i++)
             ind[i] = realdata[i] * win[i];
 
-        plan_forward = fftw_plan_dft_r2c_1d(length, ind, out, FFTW_ESTIMATE);
+        plan_forward = fftw_plan_dft_r2c_1d(length-1, ind, out, FFTW_ESTIMATE);
 
         fftw_execute(plan_forward);