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import math
def func(x):
return x**3 - 10.0* x*x + 5
def bisect(f, x1, x2, epsilon=1.0e-9):
f1 = f(x1)
f2 = f(x2)
if f1*f2 > 0.0:
print( 'x1 ans x2 are on the same side of x-axis')
return None
n = math.ceil(math.log(abs(x2 - x1)/epsilon)/math.log(2.0))
n = int(n)
for i in range(n):
x3 = 0.5 * (x1 + x2)
f3 = f(x3)
if f3 == 0.0: return x3
if f2*f3 < 0.0:
x1 = x3
f1 = f3
else:
x2 =x3
f2 = f3
return (x1 + x2)/2.0
print( bisect(func, 0.70, 0.8, 1.0e-4))
print( bisect(func, 0.70, 0.8, 1.0e-9))
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