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34 lines
984 B
Python
34 lines
984 B
Python
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 none of these are root and they are both positive or negative,
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# then his algorithm 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 - start) / 2.0
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while abs(start - mid) > 10**-7: # until we achieve precise 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 - start) / 2.0
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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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if __name__ == "__main__":
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print(bisection(f, 1, 1000))
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