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There are three methods that find approximately the roots of a non-linear function
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Bisection.py
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Bisection.py
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import math
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def bisection(function, a, b): # finds where the function becomes 0 in [a,b] using bolzano
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start = a
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end = b
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if function(a) == 0: # one of the a or b is a root for the function
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return a
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elif function(b) == 0:
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return b
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elif function(a) * function(b) > 0: # if noone of these are root and they are both possitive or negative,
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# then his algorith can't find the root
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print("couldn't find root in [a,b]")
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return
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else:
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mid = (start + end) / 2
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while abs(start - mid) > 0.0000001: # untill we achive percise equals to 10^-7
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if function(mid) == 0:
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return mid
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elif function(mid) * function(start) < 0:
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end = mid
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else:
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start = mid
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mid = (start + end) / 2
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return mid
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def f(x):
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return math.pow(x, 3) - 2*x -5
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print(bisection(f, 1, 1000))
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Intersection.py
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Intersection.py
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import math
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def intersection(function,x0,x1): #function is the f we want to find its root and x0 and x1 are two random starting points
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x_n = x0
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x_n1 = x1
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while True:
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x_n2 = x_n1-(function(x_n1)/((function(x_n1)-function(x_n))/(x_n1-x_n)))
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if abs(x_n2 - x_n1)<0.00001 :
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return x_n2
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x_n=x_n1
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x_n1=x_n2
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def f(x):
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return math.pow(x,3)-2*x-5
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print(intersection(f,3,3.5))
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NeutonMethod.py
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NeutonMethod.py
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import math
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def newton(function,function1,startingInt): #function is the f(x) and function1 is the f'(x)
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x_n=startingInt
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while True:
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x_n1=x_n-function(x_n)/function1(x_n)
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if abs(x_n-x_n1)<0.00001:
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return x_n1
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x_n=x_n1
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def f(x):
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return math.pow(x,3)-2*x-5
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def f1(x):
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return 3*math.pow(x,2)-2
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print(newton(f,f1,3))
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