#
#     MIT No Attribution
#
#     Copyright (C) 2010-2023 Joel Andersson, Joris Gillis, Moritz Diehl, KU Leuven.
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#     Permission is hereby granted, free of charge, to any person obtaining a copy of this
#     software and associated documentation files (the "Software"), to deal in the Software
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#     permit persons to whom the Software is furnished to do so.
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#
# -*- coding: utf-8 -*-
from casadi import *

# Example on how to use the DaeBuilder class
# Joel Andersson, UW Madison 2017

# Start with an empty DaeBuilder instance
dae = DaeBuilder('rocket')

# Add input expressions
a = dae.add('a', 'parameter', 'tunable')
b = dae.add('b', 'parameter', 'tunable')
u = dae.add('u', 'input')
h = dae.add('h')
v = dae.add('v')
m = dae.add('m')

# Constants
g = 9.81 # gravity

# Set ODE right-hand-side
dae.eq(dae.der(h), v)
dae.eq(dae.der(v), (u-a*v**2)/m-g)
dae.eq(dae.der(m), -b*u**2)

# Specify initial conditions
dae.set_start('h', 0)
dae.set_start('v', 0)
dae.set_start('m', 1)

# Add meta information
dae.set_unit('h','m')
dae.set_unit('v','m/s')
dae.set_unit('m','kg')

# Print DAE
dae.disp(True)