1 files changed, 23 insertions, 0 deletions
diff --git a/fftw.bqn b/fftw.bqn
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index 0000000..40c900c
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+# FFTW-based replacement for fft.bqn
+
+plan ← "*:i32"
+
+Fn ← "/usr/lib/libfftw3.so.3"⊸•FFI
+createPlan  ← Fn plan‿"fftw_plan_dft"‿"i32"‿"*i32"‿"*f64"‿"&f64"‿"i32"‿"i32"
+destroyPlan ← Fn ""‿"fftw_destroy_plan"‿plan
+executePlan ← Fn ""‿"fftw_execute"‿plan
+
+{
+  𝕨𝕊⁼𝕩: (-𝕨1⊘≢¯1)𝕊𝕩 ;
+
+  "FFT argument must be a list or have two list cells" ! (3⌊=)◶⟨0,1,2=≠,0⟩𝕩
+  Enc ← ⍉⌽
+  𝕩 ↩ (2↑≍)⍟(2>=) 𝕩
+  dir ← -⟜¬ 𝕨≡¯1
+  sh ← 1↓≢𝕩
+  in ← ⥊ Enc 𝕩
+  plan‿out ← CreatePlan ⟨≠sh,sh,in,0¨in,dir,2⋆6⟩
+  ExecutePlan ⟨plan⟩
+  DestroyPlan ⟨plan⟩
+  ÷⟜(×´sh˙)⍟(1=dir) Enc⁼ (sh∾2) ⥊ out
+}