On Thu, Nov 20, 2008 at 4:25 PM, Wolfgang Laun [EMAIL PROTECTED] wrote:
So, calling sqrt with a real 0, should not come back with a complex
number.
Again, I think this should depend on context. In Perl5, simply
use'ing Math::Complex changes the behavior of sqrt such that
sqrt(-1) returns i.
: Mittwoch, 19. November 2008 22:24
To: [EMAIL PROTECTED]
Subject: Re: [perl #60674] sign($x) always returns 1 when $x ~~ Complex
Moritz (), Carl ():
masak what should the behaviour of sign($x) be when $x is complex?
I'd argue that it's a Failure.
Aye.
# New Ticket Created by Carl Mäsak
# Please include the string: [perl #60674]
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# URL: http://rt.perl.org/rt3/Ticket/Display.html?id=60674
masak what should the behaviour of sign($x) be when $x is complex?
masak rakudo: say
On Wed Nov 19 07:35:48 2008, masak wrote:
masak what should the behaviour of sign($x) be when $x is complex?
I'd argue that it's a Failure.
If you care about complex numbers, you usually want an angle instead,
which you can get with Complex.polar. (And it's easier to give it a
another meaning
Wolfgang ():
There is a definition for the signum function for a complex argument.
sign( z ) = z / |z| for all z != 0
sign( 0 ) = 0
See e.g. http://en.wikipedia.org/wiki/Sign_function
Shouldn't be too difficult to implement.
It isn't, and note that I also proposed it in my first email.
I
On Thu, Nov 20, 2008 at 8:34 AM, Carl Mäsak [EMAIL PROTECTED] wrote:
I guess the question is more about the programmer's expectations. Is
this a case where we serve the programmer better by returning Failure,
or by generalizing the Csign function to the complex plane?
This is parallel to the
Mark ():
I think the most sensible thing is to be consistent. sgn() fails for
non-real input as long as sqrt() returns NaN for negative input.
Change the latter behavior (via a pragma or whatever) so that sqrt()
returns complex numbers, and then sgn() should start behaving on such
numbers.
On Thu, Nov 20, 2008 at 04:31:22PM +0100, Carl Mäsak wrote:
: Mark ():
: I think the most sensible thing is to be consistent. sgn() fails for
: non-real input as long as sqrt() returns NaN for negative input.
: Change the latter behavior (via a pragma or whatever) so that sqrt()
: returns
Mark ():
I think the most sensible thing is to be consistent. sgn() fails for
non-real input as long as sqrt() returns NaN for negative input.
Change the latter behavior (via a pragma or whatever) so that sqrt()
returns complex numbers, and then sgn() should start behaving on such
numbers.
I'd rather retain the dwimmishness of p5.
$ perl -MMath::Complex -le 'print sqrt(-1)'
i
Note that I didn't have to pass in Math::Complex-make(-1,0). Just -1.
On 11/20/08, Chris Dolan [EMAIL PROTECTED] wrote:
Mark ():
I think the most sensible thing is to be consistent. sgn() fails for
HaloO,
Moritz Lenz via RT wrote:
On Wed Nov 19 07:35:48 2008, masak wrote:
masak what should the behaviour of sign($x) be when $x is complex?
I'd argue that it's a Failure.
This is a bit drastic. If one computes in the complex domain
a complex valued sign function is appropriate.
multi
If a programmer calls a function with an argument that has a
well-established type, s/he may very well expect a result according
to that type, (considering that overloading isn't just a word for not
caring about type).
So, calling sqrt with a real 0, should not come back with a complex
number.
Moritz (), Carl ():
masak what should the behaviour of sign($x) be when $x is complex?
I'd argue that it's a Failure.
Aye.
[...]
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