import math
def bisection(function, a, b): # finds where the function becomes 0 in [a,b] using bolzano
start = a
end = b
if function(a) == 0: # one of the a or b is a root for the function
return a
elif function(b) == 0:
return b
elif function(a) * function(b) > 0: # if none of these are root and they are both positive or negative,
# then his algorithm can't find the root
print("couldn't find root in [a,b]")
return
else:
mid = (start + end) / 2
while abs(start - mid) > 10**-7: # until we achieve precise equals to 10^-7
if function(mid) == 0:
return mid
elif function(mid) * function(start) < 0:
end = mid
else:
start = mid
mid = (start + end) / 2
return mid
def f(x):
return math.pow(x, 3) - 2*x - 5
if __name__ == "__main__":
print(bisection(f, 1, 1000))