cos and sin calls for computing fourier term now precomputed

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/state.h b/lib/state.h
index b40b85c..76d3e5a 100644
--- a/lib/state.h
+++ b/lib/state.h
@@ -23,6 +23,9 @@ class state_t {
     v_t last_cluster_size;
     typename X_t::F_t *ReF;
     typename X_t::F_t *ImF;
+    // updating fourier terms F requires many cos and sin calls, faster to do it beforehand.
+    double *precomputed_cos;
+    double *precomputed_sin;
 
     std::function <double(X_t, X_t)> J;
     std::function <double(X_t)> H;
@@ -47,6 +50,12 @@ class state_t {
         ReF[i] = scalar_multiple(0, spins[0]);
         ImF[i] = scalar_multiple(0, spins[0]);
       }
+      precomputed_cos = (double *)malloc(L * sizeof(double));
+      precomputed_sin = (double *)malloc(L * sizeof(double));
+      for (L_t i = 0; i < L; i++) {
+        precomputed_cos[i] = cos(2 * M_PI * (double)i / (double)L);
+        precomputed_sin[i] = sin(2 * M_PI * (double)i / (double)L);
+      }
     }
 
     ~state_t() {
@@ -63,6 +72,8 @@ class state_t {
       }
       free(ReF);
       free(ImF);
+      free(precomputed_sin);
+      free(precomputed_cos);
     }
 };