From 12f15f49cd8cc4ab9c809700e8cb88a0efe198d8 Mon Sep 17 00:00:00 2001
From: Jaron Kent-Dobias <jaron@kent-dobias.com>
Date: Wed, 17 Feb 2021 16:14:33 +0100
Subject: Rearranged some functions among files, and wrote the normalize
 function to take generic Eigen expressions.

---
 p-spin.hpp | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

(limited to 'p-spin.hpp')

diff --git a/p-spin.hpp b/p-spin.hpp
index 480b3ca..bd3cacc 100644
--- a/p-spin.hpp
+++ b/p-spin.hpp
@@ -5,6 +5,11 @@
 #include "tensor.hpp"
 #include "factorial.hpp"
 
+template <typename Derived>
+Vector<typename Derived::Scalar> normalize(const Eigen::MatrixBase<Derived>& z) {
+  return z * sqrt((double)z.size() / (typename Derived::Scalar)(z.transpose() * z));
+}
+
 template <class Scalar, int p>
 std::tuple<Scalar, Vector<Scalar>, Matrix<Scalar>> hamGradHess(const Tensor<Scalar, p>& J, const Vector<Scalar>& z) {
   Matrix<Scalar> Jz = contractDown(J, z); // Contracts J into p - 2 copies of z.
@@ -21,14 +26,8 @@ std::tuple<Scalar, Vector<Scalar>, Matrix<Scalar>> hamGradHess(const Tensor<Scal
 }
 
 template <class Scalar>
-Vector<Scalar> normalize(const Vector<Scalar>& z) {
-  return z * sqrt((double)z.size() / (Scalar)(z.transpose() * z));
-}
-
-template <class Scalar>
-Vector<Scalar> project(const Vector<Scalar>& z, const Vector<Scalar>& x) {
-  Scalar xz = x.transpose() * z;
-  return x - (xz / z.squaredNorm()) * z.conjugate();
+Vector<Scalar> zDot(const Vector<Scalar>& z, const Vector<Scalar>& dH) {
+  return -dH.conjugate() + (dH.dot(z) / z.squaredNorm()) * z.conjugate();
 }
 
 template <class Scalar, int p>
@@ -37,7 +36,7 @@ std::tuple<double, Vector<Scalar>> WdW(const Tensor<Scalar, p>& J, const Vector<
   Matrix<Scalar> ddH;
   std::tie(std::ignore, dH, ddH) = hamGradHess(J, z);
 
-  Vector<Scalar> dzdt = project(z, dH.conjugate().eval());
+  Vector<Scalar> dzdt = zDot(z, dH);
 
   double a = z.squaredNorm();
   Scalar A = (Scalar)(z.transpose() * dzdt) / a;
-- 
cgit v1.2.3-54-g00ecf