From cbcb39ff19c441a770671e151218330d1ac7bc91 Mon Sep 17 00:00:00 2001
From: Ian Jauslin <ian.jauslin@rutgers.edu>
Date: Sat, 22 Apr 2023 15:04:02 -0400
Subject: Remove term that sums up to 0 from alpha

---
 src/navier-stokes.c | 33 ++-------------------------------
 src/navier-stokes.h |  4 +---
 2 files changed, 3 insertions(+), 34 deletions(-)

(limited to 'src')

diff --git a/src/navier-stokes.c b/src/navier-stokes.c
index 6e386a3..110ba07 100644
--- a/src/navier-stokes.c
+++ b/src/navier-stokes.c
@@ -129,7 +129,7 @@ int eea(
     ns_step(u, K1, K2, N1, N2, nu, delta, L, g, fft1, fft2, ifft, tmp1, tmp2, tmp3, irreversible);
 
     energy=compute_energy(u, K1, K2);
-    alpha=compute_alpha_fast(u, K1, K2, g, L);
+    alpha=compute_alpha(u, K1, K2, g, L);
     enstrophy=compute_enstrophy(u, K1, K2, L);
     
     // running average
@@ -429,7 +429,7 @@ int ns_rhs(
   if (irreversible) {
     alpha=nu;
   } else {
-    alpha=compute_alpha(u,K1,K2,N1,N2,g,L,ifft.fft);
+    alpha=compute_alpha(u,K1,K2,g,L);
   }
 
   for(i=0; i<(K1+1)*(2*K2+1); i++){
@@ -557,35 +557,6 @@ int ns_T_nofft(
 
 // compute alpha
 double compute_alpha(
-  _Complex double* u,
-  int K1,
-  int K2,
-  int N1,
-  int N2,
-  _Complex double* g,
-  double L,
-  _Complex double* T
-){
-  _Complex double num=0;
-  double denom=0;
-  int kx,ky;
-
-  num=0.;
-  denom=0.;
-
-  for(kx=-K1;kx<=K1;kx++){
-    for(ky=-K2;ky<=K2;ky++){
-      num+=(L*L/4/M_PI/M_PI*(kx*kx+ky*ky)*getval_sym(g, kx,ky,K2)+sqrt(kx*kx+ky*ky)*T[klookup(kx,ky,N1,N2)])*conj(getval_sym(u, kx,ky,K2));
-      denom+=__real__ (kx*kx+ky*ky)*(kx*kx+ky*ky)*getval_sym(u, kx,ky,K2)*conj(getval_sym(u, kx,ky,K2));
-    }
-  }
-
-  return __real__ num/denom;
-}
-
-// compute alpha
-// do not include the term involving T, which, in the limit K->infty, vanishes
-double compute_alpha_fast(
   _Complex double* u,
   int K1,
   int K2,
diff --git a/src/navier-stokes.h b/src/navier-stokes.h
index 6f14bc8..d12f908 100644
--- a/src/navier-stokes.h
+++ b/src/navier-stokes.h
@@ -48,9 +48,7 @@ int ns_T( _Complex double* u, int K1, int K2, int N1, int N2, fft_vect fft1, fft
 int ns_T_nofft( _Complex double* out, _Complex double* u, int K1, int K2, int N1, int N2);
 
 // compute alpha
-double compute_alpha( _Complex double* u, int K1, int K2, int N1, int N2, _Complex double* g, double L, _Complex double* T);
-// do not include the term involving T, which, in the limit K->infty, vanishes
-double compute_alpha_fast( _Complex double* u, int K1, int K2, _Complex double* g, double L);
+double compute_alpha( _Complex double* u, int K1, int K2, _Complex double* g, double L);
 // compute energy
 double compute_energy( _Complex double* u, int K1, int K2);
 // compute enstrophy
-- 
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