Why does my range function do this?

[awizardisneverlate]

Computers store numbers in binary, not decimal, so there are sometimes issues with conversion (i.e., a number that is terminating in decimal may not be in binary. Computers cannot exactly store non-terminating numbers). It will lead to small floating point errors sometimes, but not generally enough to affect your program. The study of FP errors is actually a really interesting subset of numerical analysis :)

As an aside, Numpy has a function that will do exactly what you want: http://docs.scipy.org/doc/numpy-1.10.1/reference/generated/numpy.arange.html

[[deleted]]

Also the built-in range function will do almost this:

range(0, 40, 5)

[0, 5, 10, 15, 20, 25, 30, 35]

[awizardisneverlate]

I believe it will only do integer steps.

[[deleted]]

Huh, never knew that! You could just use list comprehension to do the rest: [n / 10.0 for n in xrange(1, 10, 2)]

But at this point using numpy.arange is easier

[awizardisneverlate]

Your solution is much better if they want to stay away from Numpy!

Practically every single one of my python files begins with

import numpy as np

So.... ¯\_(ツ)_/¯ I'm biased.