From 7bd8f97aea0545c3d0da438cde3fd3d7ba4083b4 Mon Sep 17 00:00:00 2001
From: Jaron Kent-Dobias <jaron@kent-dobias.com>
Date: Thu, 17 Apr 2025 17:45:26 -0300
Subject: Started implementing log-Fourier method, not working right now.

---
 fourier.hpp | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

(limited to 'fourier.hpp')

diff --git a/fourier.hpp b/fourier.hpp
index 791953b..22a57e7 100644
--- a/fourier.hpp
+++ b/fourier.hpp
@@ -4,6 +4,7 @@
 #include <complex>
 #include <vector>
 #include <tuple>
+#include <gsl/gsl_sf_gamma.h>
 
 #ifndef FFTW_THREADS
 #define FFTW_THREADS 1
@@ -36,6 +37,37 @@ public:
   std::vector<Real> convolve(const std::vector<Real>& Γh, const std::vector<Real>& R);
 };
 
+class LogarithmicFourierTransform {
+private:
+  Complex* a;
+  Complex* â;
+  fftw_plan a_to_â;
+  fftw_plan â_to_a;
+  unsigned N;
+  Real k;
+  Real Δτ;
+  Real Δω;
+  Real Δs;
+  Real τₛ;
+  Real ωₛ;
+  Real sₛ;
+public:
+  LogarithmicFourierTransform(unsigned N, Real k, Real Δω, Real Δτ, Real Δs);
+  ~LogarithmicFourierTransform();
+  Real τ(unsigned n) const;
+  Real ω(unsigned n) const;
+  Real t(unsigned n) const;
+  Real ν(unsigned n) const;
+  Real s(unsigned n) const;
+  std::vector<Complex> fourier(const std::vector<Real>& c, bool symmetric);
+  std::vector<Complex> fourier();
+  std::vector<Real> inverse(const std::vector<Complex>& ĉ);
+  void writeToA(unsigned i, Real ai);
+  std::vector<Real> convolve(const std::vector<Real>& Γh, const std::vector<Real>& R);
+};
+
+Complex gamma(Complex z);
+
 std::string fourierFile(std::string prefix, unsigned p, unsigned s, Real λ, Real τ₀, Real y, unsigned log2n, Real τₘₐₓ);
 Real energy(const std::vector<Real>& C, const std::vector<Real>& R, unsigned p, unsigned s, Real λ, Real y, Real Δτ);
 std::tuple<std::vector<Complex>, std::vector<Complex>> RddfCtdfCt(FourierTransform& fft, const std::vector<Real>& C, const std::vector<Real>& R, unsigned p, unsigned s, Real λ);
-- 
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