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falseposition.py
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falseposition.py
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from sympy import symbols, lambdify
import math
def regulaFalsi():
print("\n")
x = symbols('x')
functionString = str(input("Enter the function in the form \'x**3 - 5*x - 9\': "))
expression = lambdify(x, functionString, "math")
maxIterations = int(input("Enter maximum number of iterations: "))
accuracy = float(input("Enter the desired tolerance: "))
x1 = float(input("Enter the first guess: "))
x2 = float(input("Enter the second guess: "))
if expression(x1) * expression(x2) > 0:
print("The expression has the same sign on both the given points. Please choose another pair of starting points.\nPress enter to cotinue")
delay = input()
return False
count = 0
fx3 = 0.0
x3 = 0.0
print("\nS. No.\tx1\t\tx2\t\tx3\t\tf(x3)")
while True:
x3 = x1 - ((x2 - x1) * expression(x1)) / (expression(x2) - expression(x1))
fx3 = expression(x3)
print("{0}\t{1:.8f}\t{2:.8f}\t{3:.8f}\t{4:.8f}".format(count+1, x1, x2, x3, fx3))
if expression(x1) * fx3 < 0:
x2 = x3
else:
x1 = x3
count += 1
if (abs(fx3) < accuracy) or (count >= maxIterations):
break
print("\nAfter {0} iterations, the root of the given equation is\n x = {1}\nf(x) = {2}\n\n".format(count, x3, fx3))
return True