# ****************************************************************************
# 
# ALPS Project: Algorithms and Libraries for Physics Simulations
# 
# ALPS Libraries
# 
# Copyright (C) 2009-2010 by Matthias Troyer <troyer@phys.ethz.ch> 
# 
# This software is part of the ALPS libraries, published under the ALPS
# Library License; you can use, redistribute it and/or modify it under
# the terms of the license, either version 1 or (at your option) any later
# version.
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# the ALPS Libraries; see the file LICENSE.txt. If not, the license is also
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import pyalps
import matplotlib.pyplot as plt
import pyalps.plot

#prepare the input parameters
parms = []
for h in [0., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 3.25, 3.5]:
    parms.append(
        { 
          'LATTICE'        : "ladder", 
          'MODEL'          : "spin",
          'local_S'        : 0.5,
          'T'              : 0.08,
          'J0'             : 1 ,
          'J1'             : 1 ,
          'THERMALIZATION' : 1000,
          'SWEEPS'         : 10000,
          'L'              : 20,
          'h'              : h
        }
    )

#write the input file and run the simulation
input_file = pyalps.writeInputFiles('parm3b',parms)
res = pyalps.runApplication('dirloop_sse',input_file,Tmin=5)

#load the magnetization and collect it as function of field h
data = pyalps.loadMeasurements(pyalps.getResultFiles(prefix='parm3b'),'Magnetization Density')
magnetization = pyalps.collectXY(data,x='h',y='Magnetization Density')

#make plot
plt.figure()
pyalps.plot.plot(magnetization)
plt.xlabel('Field $h$')
plt.ylabel('Magnetization $m$')
plt.ylim(0.0,0.5)
plt.title('Quantum Heisenberg ladder')
plt.show()