From 1a2813cf5b3e6e5e19baddec6fe1386a205d1463 Mon Sep 17 00:00:00 2001
From: Pablo Piskunow <pablo.perez.piskunow@gmail.com>
Date: Mon, 26 Aug 2019 14:47:00 +0200
Subject: [PATCH] use less memory to build the moments matrix for all energies
---
kwant/kpm.py | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/kwant/kpm.py b/kwant/kpm.py
index db19f4ea..a897c8f9 100644
--- a/kwant/kpm.py
+++ b/kwant/kpm.py
@@ -731,23 +731,25 @@ class Correlator:
g_kernel[0] /= 2
mu_kernel = np.outer(g_kernel, g_kernel) * self.moments_matrix
- e = (self.energies - self._b) / self._a
+ e_scaled = (self.energies - self._b) / self._a
- # arrays for faster calculation
- sqrt_e = np.sqrt(1 - e ** 2)
- arccos_e = np.arccos(e)
+ m_array = np.arange(n_moments)
+ def _integral_factor(e):
+ # arrays for faster calculation
+ sqrt_e = np.sqrt(1 - e ** 2)
+ arccos_e = np.arccos(e)
- exp_n = np.exp(1j * np.outer(arccos_e, np.arange(n_moments)))
- t_n = np.real(exp_n)
+ exp_n = np.exp(1j * arccos_e * m_array)
+ t_n = np.real(exp_n)
- e_plus = (np.outer(e, np.ones(n_moments)) -
- 1j * np.outer(sqrt_e, np.arange(n_moments)))
- e_plus = e_plus * exp_n
+ e_plus = (e - 1j * sqrt_e * m_array)
+ e_plus = e_plus * exp_n
- big_gamma = e_plus[:, None, :] * t_n[:, :, None]
- big_gamma += big_gamma.conj().swapaxes(1, 2)
-
- self._integral_factor = np.tensordot(mu_kernel, big_gamma.T)
+ big_gamma = e_plus[None, :] * t_n[:, None]
+ big_gamma += big_gamma.conj().T
+ return np.tensordot(mu_kernel, big_gamma.T)
+ self._integral_factor = np.array([_integral_factor(e)
+ for e in e_scaled]).T
def conductivity(hamiltonian, alpha='x', beta='x', positions=None, **kwargs):
--
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