Week 5 - Curve fitting

import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit

#curve fit function
def func(t,a,b,c):
    return a*pow(t,2)+b*t+c

#Reading thermodynamic data file
def read_file():
    temperature=[]
    cp=[]
    for line in open ('data','r'):
        values=line.split(',')
        temperature.append(float(values[0]))
        cp.append(float(values[1]))
    return[temperature,cp]

#main program
temperature,cp=read_file()
popt,pcov=curve_fit(func,temperature,cp)
fit_cp=func(np.array(temperature),*popt)

plt.plot(temperature,cp,color="blue",linewidth=3)
plt.plot(temperature,fit_cp,color="red",linewidth=3)
plt.legend(['Actual data','curvefit'])
plt.xlabel('Temperature[k]')
plt.ylabel('cp')
plt.show()
Program:(3rd order)
import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit

#curve fit function
def func(t,a,b,c,d):
    return a*pow(t,3)+b*pow(t,2)+c*t+d

#Reading thermodynamic data file
def read_file():
    temperature=[]
    cp=[]
    for line in open ('data','r'):
        values=line.split(',')
        temperature.append(float(values[0]))
        cp.append(float(values[1]))
    return[temperature,cp]

#main program
temperature,cp=read_file()
popt,pcov=curve_fit(func,temperature,cp)
fit_cp=func(np.array(temperature),*popt)

plt.plot(temperature,cp,color="blue",linewidth=3)
plt.plot(temperature,fit_cp,color="red",linewidth=3)
plt.legend(['Actual data','curvefit'])
plt.xlabel('Temperature[k]')
plt.ylabel('cp')
plt.show()
Program:(4th order)
import numpy as np
import matplotlib.pyplot as plt
from scipy.optimize import curve_fit

#curve fit function
def func(t,a,b,c,d,e):
    return a*pow(t,4)+b*pow(t,3)+c*pow(t,2)+d*t+e

#Reading thermodynamic data file
def read_file():
    temperature=[]
    cp=[]
    for line in open ('data','r'):
        values=line.split(',')
        temperature.append(float(values[0]))
        cp.append(float(values[1]))
    return[temperature,cp]

#main program
temperature,cp=read_file()
popt,pcov=curve_fit(func,temperature,cp)
fit_cp=func(np.array(temperature),*popt)

plt.plot(temperature,cp,color="blue",linewidth=3)
plt.plot(temperature,fit_cp,color="red",linewidth=3)
plt.legend(['Actual data','curvefit'])
plt.xlabel('Temperature[k]')
plt.ylabel('cp')
plt.show()