From 69d33f4cc316dd47404f1bcf0178e59fe8d2c076 Mon Sep 17 00:00:00 2001
From: Jaron Kent-Dobias <jaron@kent-dobias.com>
Date: Sat, 5 Apr 2025 11:01:37 -0300
Subject: Slightly better memory efficiency

---
 fourier.cpp | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

(limited to 'fourier.cpp')

diff --git a/fourier.cpp b/fourier.cpp
index d2f9ad8..1bef4b9 100644
--- a/fourier.cpp
+++ b/fourier.cpp
@@ -45,6 +45,15 @@ std::vector<Complex> FourierTransform::fourier(const std::vector<Real>& c) {
   return ĉ;
 }
 
+std::vector<Complex> FourierTransform::fourier() {
+  fftw_execute(plan_r2c);
+  std::vector<Complex> ĉ(â.size());
+  for (unsigned i = 0; i < â.size(); i++) {
+    ĉ[i] = â[i] * (Δτ * M_PI);
+  }
+  return ĉ;
+}
+
 std::vector<Real> FourierTransform::inverse(const std::vector<Complex>& ĉ) {
   â = ĉ;
   fftw_execute(plan_c2r);
@@ -55,6 +64,10 @@ std::vector<Real> FourierTransform::inverse(const std::vector<Complex>& ĉ) {
   return c;
 }
 
+void FourierTransform::writeToA(unsigned i, Real ai) {
+  a[i] = ai;
+}
+
 std::string fourierFile(std::string prefix, unsigned p, unsigned s, Real λ, Real τ₀, Real y, unsigned log2n, Real τₘₐₓ) {
   return prefix + "_" + std::to_string(p) + "_" + std::to_string(s) + "_" + std::to_string(λ) + "_" + std::to_string(τ₀) + "_" + std::to_string(y) + "_" + std::to_string(log2n) + "_" + std::to_string(τₘₐₓ) + ".dat";
 }
@@ -70,17 +83,18 @@ Real energy(const std::vector<Real>& C, const std::vector<Real>& R, unsigned p,
 }
 
 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) {
-  std::vector<Real> RddfC(C.size());
   for (unsigned i = 0; i < C.size() / 2; i++) {
-    RddfC[i] = R[i] * ddf(λ, p, s, C[i]);
+    fft.writeToA(i,  R[i] * ddf(λ, p, s, C[i]));
+  }
+  for (unsigned i = C.size() / 2; i < C.size(); i++) {
+    fft.writeToA(i, 0);
   }
-  std::vector<Complex> RddfCt = fft.fourier(RddfC);
+  std::vector<Complex> RddfCt = fft.fourier();
 
-  std::vector<Real> dfC(C.size());
   for (unsigned i = 0; i < C.size(); i++) {
-    dfC[i] = df(λ, p, s, C[i]);
+    fft.writeToA(i, df(λ, p, s, C[i]));
   }
-  std::vector<Complex> dfCt = fft.fourier(dfC);
+  std::vector<Complex> dfCt = fft.fourier();
 
   return {RddfCt, dfCt};
 }
-- 
cgit v1.2.3-70-g09d2