python - Why time.time() gives 0.0?

Question

I have a python program defined by a function myFunc(m,n)

Basically, the function contains two for loops.

def myFunc(m, n) : 
    for i in range(m) : 
        for j in range(n) : 
            # do it ...
    return 

I would like to calculate the time elapsed for m,n=20,20

I do it like this:

start_time = time.time()
b = myFunc(m,n)
elapsed_time = time.time() - start_time
print elapsed_time

The result is 0.0 almost always. Why?

Answer 1

Because time.time() - time.time() will be 0.0 when myFunc doesn't take very long.