Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 6/20/2016 5:59 PM, Nathaniel Smith wrote: If you have the time to check for existing bug reports about this, and file a new bug if you don't find one, then it'd be appreciated. https://github.com/numpy/numpy/issues/7770 Alan ___ NumPy-Discussion

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mo, 2016-06-20 at 15:15 -0700, Nathaniel Smith wrote: > On Mon, Jun 20, 2016 at 3:09 PM,   wrote: > > > > On Mon, Jun 20, 2016 at 4:31 PM, Alan Isaac > > wrote: > > > > > > On 6/13/2016 1:54 PM, Marten van Kerkwijk wrote: > > > > > > > > > > > >

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, Jun 20, 2016 at 3:09 PM, wrote: > On Mon, Jun 20, 2016 at 4:31 PM, Alan Isaac wrote: >> On 6/13/2016 1:54 PM, Marten van Kerkwijk wrote: >>> >>> 1. What in principle is the best return type for int ** int (which >>> Josef I think most properly

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, Jun 20, 2016 at 4:31 PM, Alan Isaac wrote: > On 6/13/2016 1:54 PM, Marten van Kerkwijk wrote: >> >> 1. What in principle is the best return type for int ** int (which >> Josef I think most properly rephrased as whether `**` should be >> thought of as a float

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, Jun 20, 2016 at 2:11 PM, Alan Isaac wrote: > On 6/10/2016 8:28 PM, Allan Haldane wrote: >> >> My understanding is that numpy never upcasts based on the values, it >> upcasts based on the datatype ranges. >> >>

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 6/10/2016 8:28 PM, Allan Haldane wrote: My understanding is that numpy never upcasts based on the values, it upcasts based on the datatype ranges. http://docs.scipy.org/doc/numpy-1.10.1/reference/ufuncs.html#casting-rules >>> (np.int64(2**6)*np.arange(5,dtype=np.int8)).dtype

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 6/13/2016 1:54 PM, Marten van Kerkwijk wrote: 1. What in principle is the best return type for int ** int (which Josef I think most properly rephrased as whether `**` should be thought of as a float operator, like `/` in python3 and `sqrt` etc.); Perhaps the question is somewhat different.

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Jun 13, 2016 10:54 AM, "Marten van Kerkwijk" wrote: > > Hi All, > > ​I think we're getting a little off the rails, perhaps because two questions are being conflated: > > 1. What in principle is the best return type for int ** int (which Josef I think most properly

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

Hi All, ​I think we're getting a little off the rails, perhaps because two questions are being conflated: 1. What in principle is the best return type for int ** int (which Josef I think most properly rephrased as whether `**` should be thought of as a float operator, like `/` in python3 and

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 06/13/2016 05:05 AM, V. Armando Solé wrote: > On 11/06/2016 02:28, Allan Haldane wrote: >> >> So as an extra twist in this discussion, this means numpy actually >> *does* return a float value for an integer power in a few cases: >> >> >>> type( np.uint64(2) ** np.int8(3) ) >>

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, Jun 13, 2016 at 12:07 PM, wrote: > > > On Mon, Jun 13, 2016 at 11:51 AM, wrote: > >> >> >> On Mon, Jun 13, 2016 at 11:25 AM, Antoine Pitrou >> wrote: >> >>> On Mon, 13 Jun 2016 10:49:44 -0400 >>> josef.p...@gmail.com

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, Jun 13, 2016 at 11:51 AM, wrote: > > > On Mon, Jun 13, 2016 at 11:25 AM, Antoine Pitrou > wrote: > >> On Mon, 13 Jun 2016 10:49:44 -0400 >> josef.p...@gmail.com wrote: >> > >> > My argument is that `**` is like integer division and sqrt where

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, Jun 13, 2016 at 11:25 AM, Antoine Pitrou wrote: > On Mon, 13 Jun 2016 10:49:44 -0400 > josef.p...@gmail.com wrote: > > > > My argument is that `**` is like integer division and sqrt where the > domain > > where integer return are the correct numbers is too small to

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, 13 Jun 2016 10:49:44 -0400 josef.p...@gmail.com wrote: > > My argument is that `**` is like integer division and sqrt where the domain > where integer return are the correct numbers is too small to avoid > headaches by users. float64 has less integer precision than int64: >>>

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, Jun 13, 2016 at 10:05 AM, Alan Isaac wrote: > On 6/13/2016 4:47 AM, Antoine Pitrou wrote: > >> Currently, the choice is simple: if you want an int output, >> have an int input; if you want a float output, have a float output. >> > > > That is a misunderstanding,

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, 13 Jun 2016 10:05:08 -0400 Alan Isaac wrote: > > That is a misunderstanding, which may be influencing the discussion. > Examples of complications: > > >>> type(np.int8(2)**2) > > >>> type(np.uint64(2)**np.int8(2)) > The `uint64 x int8 -> float64` is IMHO an

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 6/13/2016 4:47 AM, Antoine Pitrou wrote: Currently, the choice is simple: if you want an int output, have an int input; if you want a float output, have a float output. That is a misunderstanding, which may be influencing the discussion. Examples of complications: >>> type(np.int8(2)**2)

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 11/06/2016 02:28, Allan Haldane wrote: So as an extra twist in this discussion, this means numpy actually *does* return a float value for an integer power in a few cases: >>> type( np.uint64(2) ** np.int8(3) ) numpy.float64 Shouldn't that example end up the discussion? I find

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Fri, 10 Jun 2016 20:28:30 -0400 Allan Haldane wrote: > > Also, I like to think of numpy as having quite C-like behavior, allowing > you to play with the lowlevel bits and bytes. (I actually wish its > casting behavior was more C-like). I suspect that people working

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Fr, 2016-06-10 at 20:16 +, Ian Henriksen wrote: > On Fri, Jun 10, 2016 at 12:01 PM Nathaniel Smith > wrote: > > On Jun 10, 2016 10:50, "Alan Isaac" wrote: > > > > > > On 6/10/2016 1:34 PM, Nathaniel Smith wrote: > > >> > > >> You keep pounding on this

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

I do think one of the main arguments for returning float remains the analogy with division. I don't know about the rest of you, but it has been such a relief not to have to tell students any more "you should add a ".", otherwise it does integer division". For most purposes, it simply shouldn't

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 06/10/2016 03:38 PM, Alan Isaac wrote: np.find_common_type([np.int8],[np.int32]) > dtype('int8') (np.arange(10,dtype=np.int8)+np.int32(2**10)).dtype > dtype('int16') > > And so on. If these other binary operators upcast based > on the scalar value, why wouldn't exponentiation? > I

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Fri, Jun 10, 2016 at 12:01 PM Nathaniel Smith wrote: > On Jun 10, 2016 10:50, "Alan Isaac" wrote: > > > > On 6/10/2016 1:34 PM, Nathaniel Smith wrote: > >> > >> You keep pounding on this example. It's a fine example, but, c'mon. **2 > is probably at

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 06/10/2016 01:50 PM, Alan Isaac wrote: > Again, **almost all** integer combinations overflow: that's the point. Don't almost all integer combinations overflow for multiplication as well? I estimate that for unsigned 32 bit integers, only roughly 1 in 2e8 combinations don't overflow. The

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

I guess I have one more question; sorry. Suppose we stipulate that `np.int_(9)**np.int__(10)` should just overflow, since that appears to be the clear intent of the (informed) user. When a Python 3 user writes `np.arange(10)**10`, how are we to infer the intended type of the output? (I specify

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Fri, Jun 10, 2016 at 2:00 PM, Nathaniel Smith wrote: > On Jun 10, 2016 10:50, "Alan Isaac" wrote: > > > > On 6/10/2016 1:34 PM, Nathaniel Smith wrote: > >> > >> You keep pounding on this example. It's a fine example, but, c'mon. **2 > is probably at

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Jun 10, 2016 10:50, "Alan Isaac" wrote: > > On 6/10/2016 1:34 PM, Nathaniel Smith wrote: >> >> You keep pounding on this example. It's a fine example, but, c'mon. **2 is probably at least 100x more common in real source code. Maybe 1000x more common. Why should we break

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 6/10/2016 1:34 PM, Nathaniel Smith wrote: You keep pounding on this example. It's a fine example, but, c'mon. **2 is probably at least 100x more common in real source code. Maybe 1000x more common. Why should we break the common case for your edge case? It is hardly an "edge case".

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 6/10/2016 1:20 PM, Allan Haldane wrote: numpy users have to be aware of overflow issues in lots of other (simple) cases anyway, eg plain addition and multiplication. This is not comparable because *almost all* integer combinations overflow for exponentiation. See the discussion at

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Jun 10, 2016 05:11, "Alan Isaac" wrote: > > On 6/10/2016 2:42 AM, Nathaniel Smith wrote: >> >> I dunno, with my user hat on I'd be incredibly surprised / confused / >> annoyed if an innocent-looking expression like >> >> np.arange(10) ** 2 >> >> started returning

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 6/10/2016 1:20 PM, Ian Henriksen wrote: forcing float output for people who actually want integers is not at all ideal Yes, there definitely should be a function supporting this. Alan ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Fri, Jun 10, 2016 at 12:42 AM Nathaniel Smith wrote: > On Mon, Jun 6, 2016 at 1:17 PM, Charles R Harris > wrote: > > > > > > > > On Mon, Jun 6, 2016 at 2:11 PM, Marten van Kerkwijk < > m.h.vankerkw...@gmail.com> wrote: > >> > >> Hi Chuck, > >> > >>

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 06/10/2016 08:10 AM, Alan Isaac wrote: > Is np.arange(10)**10 also "innocent looking" to a Python user? This doesn't bother me much because numpy users have to be aware of overflow issues in lots of other (simple) cases anyway, eg plain addition and multiplication. I'll add my +1 for integer

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

n@scipy.org> Subject: Re: [Numpy-discussion] Integers to integer powers, let's make a decision On 6/10/2016 2:42 AM, Nathaniel Smith wrote: > > I dunno, with my user hat on I'd be incredibly surprised / confused / > annoyed if an innocent-looking expression like > > np.arange(10

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 6/10/2016 2:42 AM, Nathaniel Smith wrote: I dunno, with my user hat on I'd be incredibly surprised / confused / annoyed if an innocent-looking expression like np.arange(10) ** 2 started returning floats... having exact ints is a really nice feature of Python/numpy as compared to

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Fri, Jun 10, 2016 at 7:42 AM, Nathaniel Smith wrote: > On Mon, Jun 6, 2016 at 1:17 PM, Charles R Harris > wrote: >> >> ... >> >> It looks to me like users want floats, while developers want the >> easy path of raising an error. Darn those users, they

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, Jun 6, 2016 at 1:17 PM, Charles R Harris wrote: > > > > On Mon, Jun 6, 2016 at 2:11 PM, Marten van Kerkwijk > wrote: >> >> Hi Chuck, >> >> I consider either proposal an improvement, but among the two I favour >> returning float for

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Mon, Jun 6, 2016 at 2:11 PM, Marten van Kerkwijk < m.h.vankerkw...@gmail.com> wrote: > Hi Chuck, > > I consider either proposal an improvement, but among the two I favour > returning float for `**`, because, like for `/`, it ensures one gets > closest to the (mathematically) true answer in

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

Hi Chuck, I consider either proposal an improvement, but among the two I favour returning float for `**`, because, like for `/`, it ensures one gets closest to the (mathematically) true answer in most cases, and makes duck-typing that much easier -- I'd like to be able to do x** y without having

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

Charles R Harris wrote: >1. Integers to negative integer powers raise an error. >2. Integers to integer powers always results in floats. 2 ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On 6/4/2016 10:23 PM, Charles R Harris wrote: From my point of view, backwards compatibility is the main reason for choosing 1, otherwise I'd pick 2. If it weren't so easy to get floating point by using floating exponents I'd probably choose differently. As an interested user, I offer a

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 9:26 PM, Nathaniel Smith wrote: > On Jun 4, 2016 7:23 PM, "Charles R Harris" > wrote: > > > [...] > > We could always try the float option and see what breaks, but I expect > there is a fair amount of code using small exponents

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Jun 4, 2016 7:23 PM, "Charles R Harris" wrote: > [...] > We could always try the float option and see what breaks, but I expect there is a fair amount of code using small exponents like 2 or 3 where it is expected that the result is still integer. I would like more

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 7:54 PM, wrote: > > > On Sat, Jun 4, 2016 at 9:16 PM, Charles R Harris < > charlesr.har...@gmail.com> wrote: > >> >> >> On Sat, Jun 4, 2016 at 6:17 PM, wrote: >> >>> >>> >>> On Sat, Jun 4, 2016 at 8:07 PM, Charles R Harris < >>>

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 9:16 PM, Charles R Harris wrote: > > > On Sat, Jun 4, 2016 at 6:17 PM, wrote: > >> >> >> On Sat, Jun 4, 2016 at 8:07 PM, Charles R Harris < >> charlesr.har...@gmail.com> wrote: >> >>> >>> >>> On Sat, Jun 4, 2016 at 5:27 PM,

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 6:17 PM, wrote: > > > On Sat, Jun 4, 2016 at 8:07 PM, Charles R Harris < > charlesr.har...@gmail.com> wrote: > >> >> >> On Sat, Jun 4, 2016 at 5:27 PM, wrote: >> >>> >>> >>> On Sat, Jun 4, 2016 at 6:10 PM, Nathaniel Smith

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 8:07 PM, Charles R Harris wrote: > > > On Sat, Jun 4, 2016 at 5:27 PM, wrote: > >> >> >> On Sat, Jun 4, 2016 at 6:10 PM, Nathaniel Smith wrote: >> >>> On Sat, Jun 4, 2016 at 2:07 PM, V. Armando Sole

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 5:27 PM, wrote: > > > On Sat, Jun 4, 2016 at 6:10 PM, Nathaniel Smith wrote: > >> On Sat, Jun 4, 2016 at 2:07 PM, V. Armando Sole wrote: >> > Also in favor of 2. Always return a float for '**' >> >> Even if we did want

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 6:10 PM, Nathaniel Smith wrote: > On Sat, Jun 4, 2016 at 2:07 PM, V. Armando Sole wrote: > > Also in favor of 2. Always return a float for '**' > > Even if we did want to switch to this, it's such a major > backwards-incompatible change that

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 2:07 PM, V. Armando Sole wrote: > Also in favor of 2. Always return a float for '**' Even if we did want to switch to this, it's such a major backwards-incompatible change that I'm not sure how we could actually make the transition without first making it an

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

Also in favor of 2. Always return a float for '**' On 04.06.2016 21:47, josef.p...@gmail.com wrote: On Sat, Jun 4, 2016 at 3:43 PM, Charles R Harris wrote: On Sat, Jun 4, 2016 at 11:22 AM, Charles R Harris wrote: Hi All, I've made a

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

> > +1 > > On Sat, Jun 4, 2016 at 10:22 AM, Charles R Harris > wrote: >> Hi All, >> >> I've made a new post so that we can make an explicit decision. AFAICT, the >> two proposals are >> >> Integers to negative integer powers raise an error. >> Integers to integer powers

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 3:49 PM, Matthew Brett wrote: > On Sat, Jun 4, 2016 at 12:47 PM, wrote: > > > > > > On Sat, Jun 4, 2016 at 3:43 PM, Charles R Harris < > charlesr.har...@gmail.com> > > wrote: > >> > >> > >> > >> On Sat, Jun 4, 2016 at 11:22

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 12:47 PM, wrote: > > > On Sat, Jun 4, 2016 at 3:43 PM, Charles R Harris > wrote: >> >> >> >> On Sat, Jun 4, 2016 at 11:22 AM, Charles R Harris >> wrote: >>> >>> Hi All, >>> >>> I've made a new

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 3:43 PM, Charles R Harris wrote: > > > On Sat, Jun 4, 2016 at 11:22 AM, Charles R Harris < > charlesr.har...@gmail.com> wrote: > >> Hi All, >> >> I've made a new post so that we can make an explicit decision. AFAICT, >> the two proposals are >>

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 11:22 AM, Charles R Harris wrote: > Hi All, > > I've made a new post so that we can make an explicit decision. AFAICT, the > two proposals are > > >1. Integers to negative integer powers raise an error. >2. Integers to integer powers

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

On Sat, Jun 4, 2016 at 10:45 AM, Nathaniel Smith wrote: > +1 > > On Sat, Jun 4, 2016 at 10:22 AM, Charles R Harris > wrote: >> Hi All, >> >> I've made a new post so that we can make an explicit decision. AFAICT, the >> two proposals are >> >> Integers

Re: [Numpy-discussion] Integers to integer powers, let's make a decision

+1 On Sat, Jun 4, 2016 at 10:22 AM, Charles R Harris wrote: > Hi All, > > I've made a new post so that we can make an explicit decision. AFAICT, the > two proposals are > > Integers to negative integer powers raise an error. > Integers to integer powers always results

[Numpy-discussion] Integers to integer powers, let's make a decision

Hi All, I've made a new post so that we can make an explicit decision. AFAICT, the two proposals are 1. Integers to negative integer powers raise an error. 2. Integers to integer powers always results in floats. My own sense is that 1. would be closest to current behavior and using a

Re: [Numpy-discussion] Integers to integer powers

On Tue, May 24, 2016 at 2:33 PM, R Schumacher wrote: > At 01:15 PM 5/24/2016, you wrote: > > On 5/24/2016 3:57 PM, Eric Moore wrote: > > Changing np.arange(10)**3 to have a non-integer dtype seems like a big > change. > > > > What about np.arange(100)**5? > > > Interesting,

Re: [Numpy-discussion] Integers to integer powers

At 01:15 PM 5/24/2016, you wrote: On 5/24/2016 3:57 PM, Eric Moore wrote: Changing np.arange(10)**3 to have a non-integer dtype seems like a big change. What about np.arange(100)**5? Interesting, one warning per instantiation (Py2.7): >>> import numpy >>> a=numpy.arange(100)**5 :1:

Re: [Numpy-discussion] Integers to integer powers

On 5/24/2016 3:57 PM, Eric Moore wrote: Changing np.arange(10)**3 to have a non-integer dtype seems like a big change. What about np.arange(100)**5? Alan Isaac ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org

Re: [Numpy-discussion] Integers to integer powers

Yes, I'm fully aware of that. I'm speaking toward changing the default result dtype. Raising an error for negative exponents is a fine idea. Changing np.arange(10)**3 to have a non-integer dtype seems like a big change. Speaking of this, that some of the integer array operation errors can be

Re: [Numpy-discussion] Integers to integer powers

On Tue, May 24, 2016 at 10:36 AM, Eric Moore wrote: > I'd say the most compelling case for it is that is how it has always worked. > How much code will break if we make that change? (Or if not break, at least > have a change in dtype?) Is that worth it? The current

Re: [Numpy-discussion] Integers to integer powers

On 5/24/2016 1:41 PM, Matthew Brett wrote: It's a well-understood promise though - you always have to be careful of integer overflow. Of course. But **almost all** cases overflow. And "well understood" assume a certain sophistication of the user, while `arange` will certainly be used by

Re: [Numpy-discussion] Integers to integer powers

On 5/24/2016 1:36 PM, Eric Moore wrote: How much code will break if we make that change? Since even arange(10)**10 is already broken, there will probably not be much new breakage. But under any of the new proposals, *something* will break. So the question is, which shows the most foresight?

Re: [Numpy-discussion] Integers to integer powers

On Tue, May 24, 2016 at 1:31 PM, Alan Isaac wrote: > On 5/24/2016 1:19 PM, Stephan Hoyer wrote: >> >> the int ** 2 example feels quite compelling to me > > > > Yes, but that one case is trivial: a*a Right, but you'd have to know to change your code when numpy makes this

Re: [Numpy-discussion] Integers to integer powers

On Tue, May 24, 2016 at 10:31 AM, Alan Isaac wrote: > Yes, but that one case is trivial: a*a an_explicit_name ** 2 is much better than an_explicit_name * an_explicit_name, though. ___ NumPy-Discussion mailing list

Re: [Numpy-discussion] Integers to integer powers

I'd say the most compelling case for it is that is how it has always worked. How much code will break if we make that change? (Or if not break, at least have a change in dtype?) Is that worth it? Eric On Tue, May 24, 2016 at 1:31 PM, Alan Isaac wrote: > On 5/24/2016

Re: [Numpy-discussion] Integers to integer powers

On 5/24/2016 1:19 PM, Stephan Hoyer wrote: the int ** 2 example feels quite compelling to me Yes, but that one case is trivial: a*a And at least as compelling is not have a**-2 fail and not being tricked by say np.arange(10)**10. The latter is a promise of hidden errors. Alan

Re: [Numpy-discussion] Integers to integer powers

On Tue, May 24, 2016 at 9:41 AM, Alan Isaac wrote: > What exactly is the argument against *always* returning float > (even for positive integer exponents)? > If we were starting over from scratch, I would agree with you, but the int ** 2 example feels quite compelling to

Re: [Numpy-discussion] Integers to integer powers

On 5/24/2016 10:03 AM, Marten van Kerkwijk wrote: The error on int ** (-int) is OK with me too (even though I prefer just returning floats). What exactly is the argument against *always* returning float (even for positive integer exponents)? Relevant context is: - int ** int will often

Re: [Numpy-discussion] Integers to integer powers

The error on int ** (-int) is OK with me too (even though I prefer just returning floats). Having a `floor_pow` function may still be good with this solution too. -- Marten ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org

Re: [Numpy-discussion] Integers to integer powers

On Thu, 19 May 2016 20:30:40 -0700 Nathaniel Smith wrote: > > Given these immutable and contradictory constraints, the last bad > option IMHO would be that we make int ** (negative int) an error in > all cases, and the error message can suggest that instead of writing > >

Re: [Numpy-discussion] Integers to integer powers

On Fri, May 20, 2016 at 6:54 PM, Nathaniel Smith wrote: > On May 20, 2016 12:44 PM, wrote: > [...] > > > > can numpy cast to float by default for power or **? > > Maybe? The question is whether there are any valid use cases for getting > ints back: > > >>>

Re: [Numpy-discussion] Integers to integer powers

On May 20, 2016 12:44 PM, wrote: [...] > > can numpy cast to float by default for power or **? Maybe? The question is whether there are any valid use cases for getting ints back: >>> np.array([1, 2, 3]) ** 2 array([1, 4, 9]) It's not 100% obvious to me but intuitively

Re: [Numpy-discussion] Integers to integer powers

Yes, I was referring to `pow`, but I had in mind the C++ version, which is overloaded: http://www.cplusplus.com/reference/cmath/pow/ Cheers, Alan On 5/20/2016 4:27 PM, Warren Weckesser wrote: C doesn't have an exponentiation operator. The C math library has pow, powf and powl, which (like

Re: [Numpy-discussion] Integers to integer powers

Hi All, As a final desired state, always returning float seems the best idea. It seems quite similar to division in this regard, where integer division works for some values, but not for all. This means not being quite consistent with python, but as Nathan pointed out, one cannot have

Re: [Numpy-discussion] Integers to integer powers

On Fri, May 20, 2016 at 4:27 PM, Warren Weckesser < warren.weckes...@gmail.com> wrote: > > > On Fri, May 20, 2016 at 4:22 PM, Alan Isaac wrote: > >> On 5/19/2016 11:30 PM, Nathaniel Smith wrote: >> >>> the last bad >>> option IMHO would be that we make int ** (negative int)

Re: [Numpy-discussion] Integers to integer powers

On Fri, May 20, 2016 at 4:22 PM, Alan Isaac wrote: > On 5/19/2016 11:30 PM, Nathaniel Smith wrote: > >> the last bad >> option IMHO would be that we make int ** (negative int) an error in >> all cases, and the error message can suggest that instead of writing >> >>

Re: [Numpy-discussion] Integers to integer powers

On 5/19/2016 11:30 PM, Nathaniel Smith wrote: the last bad option IMHO would be that we make int ** (negative int) an error in all cases, and the error message can suggest that instead of writing np.array(2) ** -2 they should instead write np.array(2) ** -2.0 (And similarly for

Re: [Numpy-discussion] Integers to integer powers

On Fri, May 20, 2016 at 3:23 PM, Charles R Harris wrote: > > > On Fri, May 20, 2016 at 1:15 PM, Nathaniel Smith wrote: > >> On Fri, May 20, 2016 at 11:35 AM, Charles R Harris >> wrote: >> > >> > >> > On Thu, May 19, 2016 at

Re: [Numpy-discussion] Integers to integer powers

On Fri, May 20, 2016 at 1:15 PM, Nathaniel Smith wrote: > On Fri, May 20, 2016 at 11:35 AM, Charles R Harris > wrote: > > > > > > On Thu, May 19, 2016 at 9:30 PM, Nathaniel Smith wrote: > >> > >> So I guess what makes this tricky is

Re: [Numpy-discussion] Integers to integer powers

On Fri, May 20, 2016 at 11:35 AM, Charles R Harris wrote: > > > On Thu, May 19, 2016 at 9:30 PM, Nathaniel Smith wrote: >> >> So I guess what makes this tricky is that: >> >> - We want the behavior to the same for multiple-element arrays, >>

Re: [Numpy-discussion] Integers to integer powers

On Fri, May 20, 2016 at 12:35 PM, Charles R Harris < charlesr.har...@gmail.com> wrote: > > > On Thu, May 19, 2016 at 9:30 PM, Nathaniel Smith wrote: > >> So I guess what makes this tricky is that: >> >> - We want the behavior to the same for multiple-element arrays, >>

Re: [Numpy-discussion] Integers to integer powers

On Thu, May 19, 2016 at 9:30 PM, Nathaniel Smith wrote: > So I guess what makes this tricky is that: > > - We want the behavior to the same for multiple-element arrays, > single-element arrays, zero-dimensional arrays, and scalars -- the > shape of the data shouldn't affect the

Re: [Numpy-discussion] Integers to integer powers

So I guess what makes this tricky is that: - We want the behavior to the same for multiple-element arrays, single-element arrays, zero-dimensional arrays, and scalars -- the shape of the data shouldn't affect the semantics of ** - We also want the numpy scalar behavior to match the Python scalar

Re: [Numpy-discussion] Integers to integer powers

On Thu, May 19, 2016 at 10:16 PM, wrote: > > > On Thu, May 19, 2016 at 5:37 PM, Charles R Harris < > charlesr.har...@gmail.com> wrote: > >> Hi All, >> >> There are currently several pull requests apropos integer arrays/scalars >> to integer powers and, because the area is

Re: [Numpy-discussion] Integers to integer powers

On Thu, May 19, 2016 at 5:37 PM, Charles R Harris wrote: > Hi All, > > There are currently several pull requests apropos integer arrays/scalars > to integer powers and, because the area is messy and involves tradeoffs, > I'd like to see some discussion here on the

[Numpy-discussion] Integers to integer powers

Hi All, There are currently several pull requests apropos integer arrays/scalars to integer powers and, because the area is messy and involves tradeoffs, I'd like to see some discussion here on the list before proceeding. *Scalars in 1.10* In [1]: 1 ** -1 Out[1]: 1.0 In [2]: int16(1) ** -1