[perl #31980] Examples
James Ghofulpo
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Is it the intended operation of the 'factorial' program on the Parrot examples page to truncate the results? Looks like a bug to me...
James Ghofulpo
General Electric Transportation Systems
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Bernhard Schmalhofer via RT
> Is it the intended operation of the 'factorial' program on the Parrot
> examples page to
> truncate the results? Looks like a bug to me...
I have checked the factorial example on
http://www.parrotcode.org/examples/pasm.html.
Starting with 13! incorrect results are indeed returned on my 32bit
Linux machine.
Should there a promotion to BigInt be taking place? on an overflow
indication?
--
/* Bernhard.S...@gmx.de */
Leopold Toetsch
Most of the examples are really old and partially outdated. I think there
should be very few PASM examples, more complex examples should be in
PIR. Regarding the factorial: using .Integer PMCs would fix it.
leo
Will Coleda
least on my box:
The first 15 factorials are:
1
2
6
24
120
720
5040
40320
362880
3628800
39916800
479001600
no bigint lib loaded
current instr.: '(null)' pc 16 ((unknown file):-1)
To address the other point, I'll reorganize the examples in the next
few days to reduce the size of the PASM and split up the PIR into
multiple pages.
Joshua Hoblitt
> I have checked the factorial example on
> http://www.parrotcode.org/examples/pasm.html.
>
> Starting with 13! incorrect results are indeed returned on my 32bit
> Linux machine.
I'm not surprised, the values listed on that webpage for !13, !14 and
!15 are wrong.
According to my lisp interpreter the correct values (Google confirmed)
are:
13! = 6227020800
14! = 87178291200
15! = 1307674368000
In case someone should be really bored, here's a link to more then you
ever wanted to know about factorials:
http://mathworld.wolfram.com/Factorial.html
Cheers,
-J
--
Bernhard Schmalhofer
>I'm not surprised, the values listed on that webpage for !13, !14 and
>!15 are wrong.
>
>According to my lisp interpreter the correct values (Google confirmed)
>are:
>
> 13! = 6227020800
> 14! = 87178291200
> 15! = 1307674368000
>
>
Well, the problem is that Parrot indeed returns the incorrect values
that are
mentioned in the webpage.
CU, Bernhard
Joshua Hoblitt
> Well, the problem is that Parrot indeed returns the incorrect values
> that are
> mentioned in the webpage.
I happen to get the correct answers out to 20! but only because I'm on
64bit hardware. The real issue is that the C standards specifies integer
overflow as undefined behavior. Supposedly, with the proper flags, you
can get gcc to give you a SIGFPE on signed overflow. AFAIK - there is
no portable way to trap the overflow. I think the best we can hope for
is automatic promotion of literals by the compiler/assembler.
-J
--
Joshua Hoblitt
--
On Sun, Sep 11, 2005 at 01:06:57PM +0200, Bernhard Schmalhofer wrote:
> Well, the problem is that Parrot indeed returns the incorrect values
> that are
> mentioned in the webpage.
I'd like to propose that we fix the n! values listed on the examples page,
change the code example to the snippet below, and add a warning about BigInt's
requiring that GMP is installed.
--
print "The first 30 factorials are:\n"
set I1, 0
set I2, 30
new P0, .BigInt
set P0, 1
REDO: inc I1
mul P0, P0, I1
print P0
print "\n"
lt I1, I2, REDO
DONE: end
--
Cheers,
-J
--
Bernhard Schmalhofer
>I'd like to propose that we fix the n! values listed on the examples page,
>change the code example to the snippet below, and add a warning about BigInt's
>requiring that GMP is installed.
>
>
Hi,
I have added information on how to provide patches to
http://www.parrotcode.org
to docs/submissions.pod.
Basically you create patches against
https://*svn*.perl.org/perl.org/docs/live/*parrotcode*/
<http://www.google.com/url?sa=D&q=https://svn.perl.org/perl.org/docs/live/parrotcode/>
(guest/guest)
and send them to webmaster at perl.org.
CU, Bernhard
Joshua Hoblitt
> I have added information on how to provide patches to
> http://www.parrotcode.org
> to docs/submissions.pod.
>
> Basically you create patches against
> https://*svn*.perl.org/perl.org/docs/live/*parrotcode*/
> <http://www.google.com/url?sa=D&q=https://svn.perl.org/perl.org/docs/live/parrotcode/>
> (guest/guest)
> and send them to webmaster at perl.org.
The guest account doesn't seem to be working from either subversion or my
web browser.
--
$ svn co --username guest --password guest https://svn.perl.org/perl.org/docs/live/parrotcode/
Authentication realm: <https://svn.perl.org:443> perl.org
Username: guest
Password for 'guest':
Authentication realm: <https://svn.perl.org:443> perl.org
Username: guest
Password for 'guest':
svn: PROPFIND request failed on '/perl.org/docs/live/parrotcode'
svn: PROPFIND of '/perl.org/docs/live/parrotcode': authorization failed (https://svn.perl.org)
--
Cheers,
-J
--
Joshua Hoblitt via RT
disappeared and it hasn't re-appeared as a PIR example either.
-J
--
Leopold Toetsch
On Feb 20, 2006, at 23:44, Joshua Hoblitt via RT wrote:
> What happened to the factorial PASM example? It seems to have
> disappeared and it hasn't re-appeared as a PIR example either.
It used bogus high numbers beyond int32 range and was just broken.
leo
Joshua Hoblitt
Only because it was using integer registers. Limiting it to low
factorial values or using Integer pmcs would resolve the issue. I'm
going to add a PIR example using Integer pmcs unless there are any
objections.
-J
--
Allison Randal via RT
Did you add the examples? I'd like to close the ticket.
Allison
Stephen Weeks
The examples aren't on the website, but examples/pasm/fact.pasm is fixed
as of r26432.