efficient computation of the smallest fourier mode by doing a magnetization-style update anytime a bond with the external field changes

1 files changed, 24 insertions, 0 deletions

diff --git a/lib/vector.h b/lib/vector.h
index 2099d28..a1084e2 100644
--- a/lib/vector.h
+++ b/lib/vector.h
@@ -37,6 +37,20 @@ void add (vector_t <q, T> *v1, vector_t <q, T> v2) {
 }
 
 template <q_t q, class T>
+void scalar_add (vector_t <q, T> *v1, T a, vector_t <q, T> v2) {
+  for (q_t i = 0; i < q; i++) {
+    v1->x[i] += a * v2.x[i];
+  }
+}
+
+template <q_t q, class T>
+void scalar_subtract (vector_t <q, T> *v1, T a, vector_t <q, T> v2) {
+  for (q_t i = 0; i < q; i++) {
+    v1->x[i] -= a * v2.x[i];
+  }
+}
+
+template <q_t q, class T>
 void subtract (vector_t <q, T> *v1, vector_t <q, T> v2) {
   for (q_t i = 0; i < q; i++) {
     v1->x[i] -= v2.x[i];
@@ -44,6 +58,16 @@ void subtract (vector_t <q, T> *v1, vector_t <q, T> v2) {
 }
 
 template <q_t q, class T>
+T norm_squared (vector_t <q, T> v) {
+  T tmp = 0;
+  for (q_t i = 0; i < q; i++) {
+    tmp += v.x[i] * v.x[i];
+  }
+
+  return tmp;
+}
+
+template <q_t q, class T>
 vector_t <q, T> scalar_multiple(v_t a, vector_t <q, T> v) {
   vector_t <q, T> multiple;
   multiple.x = (T *)malloc(q * sizeof(T));