From 1cf5550ccc1f59c66ef2f905a0a4c240adfec717 Mon Sep 17 00:00:00 2001
From: Ardavan Oskooi <ardavano@google.com>
Date: Sat, 7 Oct 2023 22:50:18 -0700
Subject: [PATCH] add flux member function for class dft_near2far in C++ and
 DftNear2Far in Python

---
 python/examples/disc_radiation_pattern.py |  3 +++
 python/simulation.py                      |  4 ++++
 src/meep.hpp                              |  3 +++
 src/near2far.cpp                          | 19 +++++++++++++++++++
 4 files changed, 29 insertions(+)

diff --git a/python/examples/disc_radiation_pattern.py b/python/examples/disc_radiation_pattern.py
index 7f1fc6ee9..4fbcfa65e 100644
--- a/python/examples/disc_radiation_pattern.py
+++ b/python/examples/disc_radiation_pattern.py
@@ -220,6 +220,9 @@ def disc_total_flux(dmat: float, h: float) -> Tuple[float, float]:
     )
 
     flux_near = mp.get_fluxes(flux_mon)[0]
+    flux_near_n2f = mp.get_fluxes(n2f_mon)[0]
+
+    print(f"flux:, {flux_near}, {flux_near_n2f}")
 
     Ptheta = radiation_pattern(sim, n2f_mon)
     plot_radiation_pattern_polar(r * r * Ptheta)
diff --git a/python/simulation.py b/python/simulation.py
index 390dc6121..074619336 100644
--- a/python/simulation.py
+++ b/python/simulation.py
@@ -783,6 +783,10 @@ def eps(self):
     def mu(self):
         return self.swigobj_attr("mu")
 
+    @property
+    def flux(self):
+        return self.swigobj_attr("flux")
+
     def flux(
         self, direction: int = None, where: Volume = None, resolution: float = None
     ):
diff --git a/src/meep.hpp b/src/meep.hpp
index cd2e01698..123e993b1 100644
--- a/src/meep.hpp
+++ b/src/meep.hpp
@@ -1378,6 +1378,9 @@ class dft_near2far {
   /* output Poynting flux of far fields */
   double *flux(direction df, const volume &where, double resolution);
 
+  /* output Poynting flux of near/monitor fields */
+  double *flux();
+
   void save_hdf5(h5file *file, const char *dprefix = 0);
   void load_hdf5(h5file *file, const char *dprefix = 0);
 
diff --git a/src/near2far.cpp b/src/near2far.cpp
index ef3676d6a..f41a841ea 100644
--- a/src/near2far.cpp
+++ b/src/near2far.cpp
@@ -553,6 +553,25 @@ double *dft_near2far::flux(direction df, const volume &where, double resolution)
   return F;
 }
 
+double *dft_near2far::flux() {
+  const size_t Nfreq = freq.size();
+  double *fl = new double[Nfreq];
+  for (size_t i = 0; i < Nfreq; ++i)
+    fl[i] = 0;
+
+  std::complex<realnum> *Edft = 0, *Hdft = 0;
+  for (dft_chunk *f = F; f; f = f->next_in_dft->next_in_dft) {
+    Edft = f->dft;
+    Hdft = f->next_in_dft->dft;
+    for (size_t k = 0; k < f->N; ++k)
+      for (size_t i = 0; i < Nfreq; ++i)
+        fl[i] += real(Edft[k * Nfreq + i] * conj(Hdft[k * Nfreq + i]));
+  }
+  double *fl_sum = new double[Nfreq];
+  sum_to_all(fl, fl_sum, int(Nfreq));
+  return fl_sum;
+}
+
 static double approxeq(double a, double b) { return fabs(a - b) < 0.5e-11 * (fabs(a) + fabs(b)); }
 
 dft_near2far fields::add_dft_near2far(const volume_list *where, const double *freq, size_t Nfreq,