def __init__(self,num_dict,den_dict,var_dict,opt_dict='all',myvar='s'):
'''
Class to represent a model of a linear time invariant
dynamical system.
Parameters
----------
opt_dict : dictionary
Represent the parameters of `num_dict` and `den_dict`
that can be optimized and their initial values.
{'A':10,'p':10}
var_dict : dictionary
Represents all parameters of `num` and `den`.
{'A':10,'p':10}
num_dict : dictionary
Represents numerator. Keys are the power of the
polynomial variable and values are a string of the
symbolic form of the coefficient. {'0':'A*p'}
den_dict : dictionary
Represents denominator. Similar to `num_dict`.
{'1':'1','0':p}
input : array
Input to the system.
'''
if type(num_dict) == type({}):
self.num_dict = num_dict
self.num_str = poly_dict_to_str(self.num_dict,myvar=myvar)
elif type(num_dict) == type(''):
self.num_str = num_dict
self.num_dict = PolyHasher(num_dict,var_dict,myvar=myvar)[1]
if type(den_dict) == type({}):
self.den_dict = den_dict
self.den_str = poly_dict_to_str(self.den_dict,myvar=myvar)
elif type(den_dict) == type(''):
self.den_str = den_dict
self.den_dict = PolyHasher(den_dict,var_dict,myvar=myvar)[1]
self.var_dict = var_dict
if opt_dict == False:
self.opt_dict = opt_dict
elif opt_dict == 'all':
self.opt_dict = self.var_dict.copy()
elif isinstance(opt_dict,dict):
self.opt_dict = opt_dict
num = exec_coeffs(self.num_dict,var_dict)
den = exec_coeffs(self.den_dict,var_dict)
TransferFunction.__init__(self,num,den)
reload(systemid)
from systemid import Model,fit_time
from systemid.data import time_data
del systemid
from controls import TransferFunction,create_step_vector
from numpy import arange
# theorectical system parameters
wn = 10.0*2*pi
z = .7
g = 2.0
num = [g*wn**2]
den = [1,2*z*wn,wn**2]
# create some data
tf = TransferFunction(num,den)
t = arange(0,2,.01)
u = create_step_vector(t, step_time=.5, amp=1.0)
y = tf.lsim(u,t)
#################################################
# start systemid
num_dict = {'0':'g*wn**2'}
den_dict = {'2':'1','1':'2*z*wn','0':'wn**2'}
var_dict = {'g':1,'z':z,'wn':10}
to_opt_dict = {'g':5,'z':z,'wn':10}
data = time_data(t,u,y)
###############################
def __repr__(self, labelstr='systemid.Model'):
return TransferFunction.__repr__(self,labelstr)
