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regula_falsi.py
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regula_falsi.py
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#Regula-Falsi Method
#MATH F313: Numerical Analysis
from math import e
def f(x):
return 5*e**-x + x - 5
import pylab as plt
import numpy as np
def inspect():
#Function to inspect the possible positions of roots
a = np.linspace(-2,1.5,100)
b = f(a)
plt.plot(a,b)
plt.show()
x1, x2 = -2.0, 1.6 # bracket values (x1,x2) = (-2,1.5)
error = 1e-6 # permissible error
i = 0 # iteration counter
x3 = 3
while abs(f(x3))>error and i < 60:
x3 = x2 - (f(x2)*(x2-x1))/(f(x2)-f(x1)) # secant formula/regula-falsi
if f(x1)*f(x3) < 0.:
x2 = x3
elif f(x2)*f(x3) < 0.:
x1 = x3
i+=1
rt = x3 # estimated root of the equation
print 'The root of the equation is ' + str(rt) + '\n' + 'f(root) = ' + str(f(rt))
print 'No. of iterations: ' + str(i)