Fix bug in r2c fft using extra planner

- This is a quick, but hacky and inefficient way to use the twiddle
  factors generated by the `Planner`, but it works.

- Add more details to assert statements for debugging

src/fft.rs

@@ -2,7 +2,6 @@
 use std::simd::prelude::f64x8;
 
 use crate::planner::{Planner32, Planner64};
-use crate::twiddles::filter_twiddles;
 use crate::{
     fft_32_with_opts_and_plan, fft_64, fft_64_with_opts_and_plan, twiddles::generate_twiddles,
     Direction, Options,
@@ -64,11 +63,13 @@ macro_rules! impl_r2c_fft {
             let mut planner = <$planner>::new(big_n, Direction::Forward);
 
             // save these for the untanngling step
-            let twiddle_re = planner.twiddles_re.clone();
-            let twiddle_im = planner.twiddles_im.clone();
+            let twiddle_re = planner.twiddles_re;
+            let twiddle_im = planner.twiddles_im;
+
+            planner = <$planner>::new(big_n / 2, Direction::Forward);
 
             // We only need (N / 2) / 2 twiddle factors for the actual FFT call, so we filter
-            filter_twiddles(&mut planner.twiddles_re, &mut planner.twiddles_im);
+            // filter_twiddles(&mut planner.twiddles_re, &mut planner.twiddles_im);
 
             let opts = Options::guess_options(z_even.len());
             $fft_w_opts_and_plan(&mut z_even, &mut z_odd, &opts, &mut planner);

src/lib.rs

@@ -92,10 +92,10 @@ macro_rules! impl_fft_interleaved_for {
     };
 }
 
-#[doc(cfg(feature = "complex-nums"))]
+// #[doc(cfg(feature = "complex-nums"))]
 #[cfg(feature = "complex-nums")]
 impl_fft_interleaved_for!(fft_32_interleaved, f32, fft_32, deinterleave_complex32);
-#[doc(cfg(feature = "complex-nums"))]
+// #[doc(cfg(feature = "complex-nums"))]
 #[cfg(feature = "complex-nums")]
 impl_fft_interleaved_for!(fft_64_interleaved, f64, fft_64, deinterleave_complex64);
 
@@ -129,7 +129,7 @@ macro_rules! impl_fft_with_opts_and_plan_for {
             opts: &Options,
             planner: &$planner,
         ) {
-            assert!(reals.len() == imags.len() && reals.len().is_power_of_two());
+            assert!(reals.len() == imags.len() && reals.len().is_power_of_two(), "reals.len() and imags.len() must be equal, and both should be a power of 2. Actual lengths - reals: {} imags: {}", reals.len(), imags.len());
             let n: usize = reals.len().ilog2() as usize;
 
             // Use references to avoid unnecessary clones
@@ -138,7 +138,7 @@ macro_rules! impl_fft_with_opts_and_plan_for {
 
             // We shouldn't be able to execute FFT if the # of twiddles isn't equal to the distance
             // between pairs
-            assert!(twiddles_re.len() == reals.len() / 2 && twiddles_im.len() == imags.len() / 2);
+            assert!(twiddles_re.len() == reals.len() / 2 && twiddles_im.len() == imags.len() / 2,"got: {} == {} and {} == {}", twiddles_re.len(), reals.len() / 2, twiddles_im.len(), imags.len() / 2);
 
             match planner.direction {
                 Direction::Reverse => {