On Sat, May 1, 2010 at 3:36 PM, Gökhan Sever <gokhansever@gmail.com> wrote:

Hello,

Is "b" an expected value? I am suspecting another floating point arithmetic issue.

I[1]: a = np.arange(1.6, 1.8, 0.1, dtype='float32')

I[2]: a

O[2]: array([ 1.60000002, 1.70000005], dtype=float32)

I[3]: b = np.arange(1.7, 1.8, 0.1, dtype='float32')

I[4]: b

O[4]: array([ 1.70000005, 1.79999995], dtype=float32)

A bit conflicting with the np.arange docstring:

"Values are generated within the half-open interval ``[start, stop)``"

(in other words, the interval including `start` but excluding `stop`).

Thanks.

--

Gökhan

Fair enough explanations to use np.linspace instead. What was confusing me above while a[1] and b[0] shows 1.70000005 only "b" steps up to 1.79999995 which "a" can't.

The following is another surprise output:

I[5]: c = np.arange(0.4, 0.5, 0.1, dtype='float32')

I[6]: c

O[6]: array([ 0.40000001], dtype=float32)

Anyways, a Slashdotter might have seen me asking these questions. I will go read What Every Programmer Should Know About Floating-Point Arithmetic article.

--

Gökhan