import math
def func(x):
        return x**3 - 10.0* x*x + 5

def rootsearch(f,a,b,dx):
    x = a
    while True:
        f1 = f(x)
        f2 = f(x+dx)
        if f1*f2 < 0:
                return x, x + dx
        x = x + dx
        if x >=  b: 
                print( 'Failed to find root')
                return

x,y = rootsearch(func, 0.0,1.0,.1)
print( x,y)
x,y = rootsearch(math.cos, 0.0, 4,.1)
print( x,y)