#!/usr/bin/env python 
# -*- coding: utf-8 -*-

# Copyright (C) 2010 Modelon AB
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, version 3 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.

import nose
import numpy.testing
from assimulo import testattr
from assimulo.lib.odepack import dsrcar, dcfode
from assimulo.solvers import LSODAR, odepack
from assimulo.problem import Explicit_Problem
from assimulo.exception import *

import numpy as N

class Test_LSODAR:
    """
    Tests the LSODAR solver.
    """
    def setUp(self):
        """
        This sets up the test case.
        """
        def f(t,y):
            eps = 1.e-6
            my = 1./eps
            yd_0 = y[1]
            yd_1 = my*((1.-y[0]**2)*y[1]-y[0])
            
            return N.array([yd_0,yd_1])
        
        def jac(t,y):
            eps = 1.e-6
            my = 1./eps
            J = N.zeros([2,2])
            
            J[0,0]=0.
            J[0,1]=1.
            J[1,0]=my*(-2.*y[0]*y[1]-1.)
            J[1,1]=my*(1.-y[0]**2)
            
            return J
        
        #Define an Assimulo problem
        y0 = [2.0,-0.6] #Initial conditions
        
        exp_mod = Explicit_Problem(f,y0)
        exp_mod_t0 = Explicit_Problem(f,y0,1.0)
        
        exp_mod.jac = jac
        self.mod = exp_mod
            
        #Define an explicit solver
        self.sim = LSODAR(exp_mod) #Create a LSODAR solve
        
        #Sets the parameters
        self.sim.atol = 1e-6 #Default 1e-6
        self.sim.rtol = 1e-6 #Default 1e-6
        self.sim.usejac = False

    @testattr(stddist = True)
    def test_simulation(self):
        """
        This tests the LSODAR with a simulation of the van der pol problem.
        """
        self.sim.simulate(1.) #Simulate 2 seconds

        nose.tools.assert_almost_equal(self.sim.y_sol[-1][0], -1.863646028, 4)
    @testattr(stddist = True)
    def test_setcoefficients(self):
        elco,tesco=dcfode(1)
        nose.tools.assert_almost_equal(elco[0,2],5./12.,9) # AM-2
        nose.tools.assert_almost_equal(tesco[0,2],2.,9) # AM-2 error coeff  
    @testattr(stddist = True)
    def test_readcommon(self):
        """
        This tests the LSODAR's subroutine dsrcar  (read functionality).
        """
        self.sim.simulate(1.) #Simulate 2 seconds
        r=N.ones((245,),'d')
        i=N.ones((55,),'i')
        dsrcar(r,i,1)
        nose.tools.assert_almost_equal(r[217], 2.22044605e-16, 20)
        nose.tools.assert_equal(i[36], 3)
        
    @testattr(stddist = True)
    def test_writereadcommon(self):
        """
        This tests the LSODAR's subroutine dsrcar  (write and read functionality).
        """
        r=N.ones((245,),'d')
        i=N.ones((55,),'i')
        dsrcar(r,i,2)
        r[0]=100.
        i[0]=10
        dsrcar(r,i,1)
        nose.tools.assert_almost_equal(r[0], 1., 4)
        nose.tools.assert_equal(i[0], 1)  
    def test_rkstarter(self):
        """
        This test checks the correctness of the Nordsieck array generated 
        from a RK starter
        """
        A=N.array([[0.,1.],[-4.,0.]])
        def f(t,x,sw0):
            return N.dot(A,N.array(x))
        H = 1.e-8
        # Compute the exact solution at h=0,H/4,H/2,3H/4,H
        T=N.array([0.,H/4.,H/2.,3./4.*H,H])
        y0=N.array([1.,0.])
        from scipy.linalg import expm
        exact=N.array([N.dot(expm(A*t),y0) for t in T])
        #polynomial interpolation
        from scipy import polyfit
        coeff = polyfit(T,exact,4)
        d1coeff=N.array([4,3,2,1]).reshape(-1,1)*coeff[:-1,:]
        d2coeff=N.array([3,2,1]).reshape(-1,1)*d1coeff[:-1,:]
        d3coeff=N.array([2,1]).reshape(-1,1)*d2coeff[:-1,:]
        d4coeff=N.array([1]).reshape(-1,1)*d3coeff[:-1,:]
        h=H/4.
        nordsieck_at_0=N.array([coeff[-1,:],h*d1coeff[-1,:],h**2/2.*d2coeff[-1,:],
                                     h**3/6.*d3coeff[-1,:],h**4/24.*d4coeff[-1,:]])
        rkNordsieck=odepack.RKStarterNordsieck(f,H)
        computed=rkNordsieck(0,y0)       
        numpy.testing.assert_allclose(computed[1], nordsieck_at_0, atol=H/100., verbose=True)                    
        
    @testattr(stddist = True)
    def test_interpol(self):
        # a with interpolation and report_continuously
        self.sim.report_continuously=True
        t_sol,y_sol=self.sim.simulate(1.,ncp_list=[0.5])
        self.sim.reset()
        t_sol1,y_sol1=self.sim.simulate(0.5)
        ind05=N.nonzero(N.array(t_sol)==0.5)[0][0]
        #print y_sol[ind05],y_sol1[-1]
        nose.tools.assert_almost_equal(y_sol[ind05,0],y_sol1[-1,0],6)
        
        
    def test_simulation_with_jac(self):
        """
        This tests the LSODAR with a simulation of the van der pol problem.
        """
        self.sim.usejac = True
        self.sim.simulate(1.) #Simulate 2 seconds

        nose.tools.assert_almost_equal(self.sim.y_sol[-1][0], -1.863646028, 4)
    
    @testattr(stddist = True)    
    def test_simulation_ncp(self):
        """
        Test a simulation with ncp.
        """
        self.sim.simulate(1.,100) #Simulate 2 seconds

        nose.tools.assert_almost_equal(self.sim.y_sol[-1][0], -1.863646028, 4)
        
    @testattr(stddist = True)    
    def test_simulation_ncp_list(self):
        """
        Test a simulation with ncp.
        """
        self.sim.simulate(1.,ncp_list=[0.5]) #Simulate 2 seconds

        nose.tools.assert_almost_equal(self.sim.y_sol[-1][0], -1.863646028, 4)
        
    @testattr(stddist = True)    
    def test_simulation_ncp_list_2(self):
        """
        Test a simulation with ncp.
        """
        self.sim.simulate(1.,ncp_list=[0.5,4]) #Simulate 2 seconds

        nose.tools.assert_almost_equal(self.sim.y_sol[-1][0], -1.863646028, 4)
        
    @testattr(stddist = True)    
    def test_simulation_ncp_with_jac(self):
        """
        Test a simulation with ncp.
        """
        self.sim.usejac= True
        self.sim.simulate(1.,100) #Simulate 2 seconds

        nose.tools.assert_almost_equal(self.sim.y_sol[-1][0], -1.863646028, 4)
