sqrt without EXPR and Math::Complex always 0

[p5pRT]

Migrated from rt.perl.org#62412 (status was 'resolved')

Searchable as RT62412$

[p5pRT]

From frank.wiegand@gmail.com

This is a bug report for perl from frank.wiegand@​gmail.com,
generated with the help of perlbug 1.36 running under perl 5.10.0.

---

perldoc -f sqrt says​:

| Return the square root of EXPR. If EXPR is omitted, returns square
| root of C<$_>. Only works on non-negative operands, unless you've
| loaded the standard Math​::Complex module.

Let's try​:

% perl -MMath​::Complex -E '$_=+1; say sqrt'
0
% perl -MMath​::Complex -E '$_=-1; say sqrt'
0

The EXPR form works fine​:

% perl -MMath​::Complex -E 'say sqrt +1'
1
% perl -MMath​::Complex -E 'say sqrt -1'
i

Without -MMath​::Complex everything works fine, according to the docs.

Thanks, Frank

---

---

Flags​:
  category=core
  severity=low

---

Site configuration information for perl 5.10.0​:

Configured by Debian Project at Thu Jan 1 15​:40​:00 UTC 2009.

Summary of my perl5 (revision 5 version 10 subversion 0) configuration​:
  Platform​:
  osname=linux, osvers=2.6.26-1-vserver-amd64,
archname=x86_64-linux-gnu-thread-multi
  uname='linux excelsior 2.6.26-1-vserver-amd64 #1 smp sat nov 8
20​:24​:14 utc 2008 x86_64 gnulinux '
  config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr
-Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
-Dsitelib=/usr/local/share/perl/5.10.0
-Dsitearch=/usr/local/lib/perl/5.10.0 -Dman1dir=/usr/share/man/man1
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl
-Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio
-Uusenm -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib
-Dlibperl=libperl.so.5.10.0 -Dd_dosuid -des'
  hint=recommended, useposix=true, d_sigaction=define
  useithreads=define, usemultiplicity=define
  useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
  use64bitint=define, use64bitall=define, uselongdouble=undef
  usemymalloc=n, bincompat5005=undef
  Compiler​:
  cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN
-fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64',
  optimize='-O2 -g',
  cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing
-pipe -I/usr/local/include'
  ccversion='', gccversion='4.3.2', gccosandvers=''
  intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
  ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
  alignbytes=8, prototype=define
  Linker and Libraries​:
  ld='cc', ldflags =' -L/usr/local/lib'
  libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
  libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
  perllibs=-ldl -lm -lpthread -lc -lcrypt
  libc=/lib/libc-2.7.so, so=so, useshrplib=true,
libperl=libperl.so.5.10.0
  gnulibc_version='2.7'
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
  cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib'

Locally applied patches​:
 

---

@​INC for perl 5.10.0​:
  /etc/perl
  /usr/local/lib/perl/5.10.0
  /usr/local/share/perl/5.10.0
  /usr/lib/perl5
  /usr/share/perl5
  /usr/lib/perl/5.10
  /usr/share/perl/5.10
  /usr/local/lib/site_perl
  .

---

Environment for perl 5.10.0​:
  HOME=/home/fw
  LANG=de_DE.UTF-8
  LANGUAGE (unset)
  LD_LIBRARY_PATH (unset)
  LOGDIR (unset)

PATH=/sbin​:/home/fw/bin​:/home/fw/bin​:/usr/local/bin​:/usr/bin​:/bin​:/usr/games
  PERL_AUTOINSTALL=--defaultdeps
  PERL_BADLANG (unset)
  PERL_EXTUTILS_AUTOINSTALL=--defaultdeps
  PERL_MM_USE_DEFAULT=1
  SHELL=/bin/zsh

[p5pRT]

From wyp3rlx02@sneakemail.com

Hi Frank,

thanks for the bug report,

Frank Wiegand wrote​:

# New Ticket Created by Frank Wiegand
# Please include the string​: [perl #62412]
# in the subject line of all future correspondence about this issue.
# <URL​: http​://rt.perl.org/rt3/Ticket/Display.html?id=62412 >

perldoc -f sqrt says​:

| Return the square root of EXPR. If EXPR is omitted, returns square
| root of C<$_>. Only works on non-negative operands, unless you've
| loaded the standard Math​::Complex module.

Let's try​:

% perl -MMath​::Complex -E '$_=+1; say sqrt'
0
% perl -MMath​::Complex -E '$_=-1; say sqrt'
0

The EXPR form works fine​:

% perl -MMath​::Complex -E 'say sqrt +1'
1
% perl -MMath​::Complex -E 'say sqrt -1'
i

Without -MMath​::Complex everything works fine, according to the docs.

This is because Math​::Complex defines a new sqrt() function that can
deal with complex values and overrides the core sqrt. The attached patch
fixes the issue and adds a test for it.

I did *not* check all other Math​::Complex functions for the same defect.

Best regards,
Steffen

[p5pRT]

From wyp3rlx02@sneakemail.com

0001-Quick-fix-for-Math-Complex-sqrt-not-falling-back.patch

From 0e83e9816665b6a5a66f31456bd554f8e0417544 Mon Sep 17 00:00:00 2001
From: Steffen Mueller <smueller@cpan.org>
Date: Fri, 16 Jan 2009 09:16:57 +0100
Subject: [PATCH] Quick fix for Math::Complex::sqrt() not falling back to $_ (RT #62412)

---
 lib/Math/Complex.pm |    2 +-
 lib/Math/Complex.t  |   10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/lib/Math/Complex.pm b/lib/Math/Complex.pm
index 7d05a44..6c5b3b4 100644
--- a/lib/Math/Complex.pm
+++ b/lib/Math/Complex.pm
@@ -672,7 +672,7 @@ sub arg {
 # Therefore if you want the two solutions use the root().
 #
 sub sqrt {
-	my ($z) = @_;
+	my ($z) = @_ ? @_ : $_;
 	my ($re, $im) = ref $z ? @{$z->_cartesian} : ($z, 0);
 	return $re < 0 ? cplx(0, CORE::sqrt(-$re)) : CORE::sqrt($re)
 	    if $im == 0;
diff --git a/lib/Math/Complex.t b/lib/Math/Complex.t
index ee02341..99514fc 100755
--- a/lib/Math/Complex.t
+++ b/lib/Math/Complex.t
@@ -106,6 +106,16 @@ push(@script, <<'EOT');
                         (Im($z) + 1          ) < $eps;
 EOT
     push(@script, qq(print "ok $test\\n"}\n));
+
+    $test++;
+    push @script, <<'TEST_FOR_DEFAULT_ARG';
+{
+    local $_ = cplx(  4,  0);
+    my $res = sqrt();
+    print "# $test $_=cplx(4, 0); sqrt() == 2\n";
+    print 'not ' if abs($res - 2) > $eps;
+TEST_FOR_DEFAULT_ARG
+    push(@script, qq(print "ok $test\\n"}\n));
 }
 
 test_mutators();
-- 
1.5.4.3

[p5pRT]

The RT System itself - Status changed from 'new' to 'open'

[p5pRT]

From wyp3rlx02@sneakemail.com

Hi Andrew, hi Jarkko,

the Porting/Maintainers.pl document in core now has a field that
indicates whether a given module considers CPAN or perl core 'upstream'.
It's not yet set for Math​::Complex. Please do set it so we know whether
to send patches to you or apply to core and let you pull them.

The attached patch fixes a minor issue in Math​::Complex and adds a test.
It's a patch against the core Math​::Complex.

Best regards,
Steffen

[p5pRT]

From wyp3rlx02@sneakemail.com

Hi Frank,

thanks for the bug report,

Frank Wiegand wrote​:

# New Ticket Created by Frank Wiegand
# Please include the string​: [perl #62412]
# in the subject line of all future correspondence about this issue.
# <URL​: http​://rt.perl.org/rt3/Ticket/Display.html?id=62412 >

perldoc -f sqrt says​:

| Return the square root of EXPR. If EXPR is omitted, returns square
| root of C<$_>. Only works on non-negative operands, unless you've
| loaded the standard Math​::Complex module.

Let's try​:

% perl -MMath​::Complex -E '$_=+1; say sqrt'
0
% perl -MMath​::Complex -E '$_=-1; say sqrt'
0

The EXPR form works fine​:

% perl -MMath​::Complex -E 'say sqrt +1'
1
% perl -MMath​::Complex -E 'say sqrt -1'
i

Without -MMath​::Complex everything works fine, according to the docs.

This is because Math​::Complex defines a new sqrt() function that can
deal with complex values and overrides the core sqrt. The attached patch
fixes the issue and adds a test for it.

I did *not* check all other Math​::Complex functions for the same defect.

Best regards,
Steffen

[p5pRT]

From wyp3rlx02@sneakemail.com

0001-Quick-fix-for-Math-Complex-sqrt-not-falling-back.patch

From 0e83e9816665b6a5a66f31456bd554f8e0417544 Mon Sep 17 00:00:00 2001
From: Steffen Mueller <smueller@cpan.org>
Date: Fri, 16 Jan 2009 09:16:57 +0100
Subject: [PATCH] Quick fix for Math::Complex::sqrt() not falling back to $_ (RT #62412)

---
 lib/Math/Complex.pm |    2 +-
 lib/Math/Complex.t  |   10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/lib/Math/Complex.pm b/lib/Math/Complex.pm
index 7d05a44..6c5b3b4 100644
--- a/lib/Math/Complex.pm
+++ b/lib/Math/Complex.pm
@@ -672,7 +672,7 @@ sub arg {
 # Therefore if you want the two solutions use the root().
 #
 sub sqrt {
-	my ($z) = @_;
+	my ($z) = @_ ? @_ : $_;
 	my ($re, $im) = ref $z ? @{$z->_cartesian} : ($z, 0);
 	return $re < 0 ? cplx(0, CORE::sqrt(-$re)) : CORE::sqrt($re)
 	    if $im == 0;
diff --git a/lib/Math/Complex.t b/lib/Math/Complex.t
index ee02341..99514fc 100755
--- a/lib/Math/Complex.t
+++ b/lib/Math/Complex.t
@@ -106,6 +106,16 @@ push(@script, <<'EOT');
                         (Im($z) + 1          ) < $eps;
 EOT
     push(@script, qq(print "ok $test\\n"}\n));
+
+    $test++;
+    push @script, <<'TEST_FOR_DEFAULT_ARG';
+{
+    local $_ = cplx(  4,  0);
+    my $res = sqrt();
+    print "# $test $_=cplx(4, 0); sqrt() == 2\n";
+    print 'not ' if abs($res - 2) > $eps;
+TEST_FOR_DEFAULT_ARG
+    push(@script, qq(print "ok $test\\n"}\n));
 }
 
 test_mutators();
-- 
1.5.4.3

[p5pRT]

From @Abigail

On Fri, Jan 16, 2009 at 09​:41​:12AM +0100, Steffen Mueller wrote​:

Hi Andrew, hi Jarkko,

the Porting/Maintainers.pl document in core now has a field that
indicates whether a given module considers CPAN or perl core 'upstream'.
It's not yet set for Math​::Complex. Please do set it so we know whether
to send patches to you or apply to core and let you pull them.

The attached patch fixes a minor issue in Math​::Complex and adds a test.
It's a patch against the core Math​::Complex.

Best regards,
Steffen

From​: Steffen Mueller <wyp3rlx02@​sneakemail.com>
To​: perl5-porters@​perl.org
Date​: Fri, 16 Jan 2009 09​:21​:29 +0100
Subject​: Re​: [perl #62412] sqrt without EXPR and Math​::Complex always 0

Hi Frank,

thanks for the bug report,

Frank Wiegand wrote​:

# New Ticket Created by Frank Wiegand
# Please include the string​: [perl #62412]
# in the subject line of all future correspondence about this issue.
# <URL​: http​://rt.perl.org/rt3/Ticket/Display.html?id=62412 >

perldoc -f sqrt says​:

| Return the square root of EXPR. If EXPR is omitted, returns square
| root of C<$_>. Only works on non-negative operands, unless you've
| loaded the standard Math​::Complex module.

Let's try​:

% perl -MMath​::Complex -E '$_=+1; say sqrt'
0
% perl -MMath​::Complex -E '$_=-1; say sqrt'
0

The EXPR form works fine​:

% perl -MMath​::Complex -E 'say sqrt +1'
1
% perl -MMath​::Complex -E 'say sqrt -1'
i

Without -MMath​::Complex everything works fine, according to the docs.

This is because Math​::Complex defines a new sqrt() function that can
deal with complex values and overrides the core sqrt. The attached patch
fixes the issue and adds a test for it.

I did *not* check all other Math​::Complex functions for the same defect.

sub sqrt {
- my ($z) = @​_;
+ my ($z) = @​_ ? @​_ : $_;

That will not pick up any lexical $_. It would if you'd used a '_' prototype​:

  sub sqrt (_) {
  my ($z) = @​_;
  ...

Abigail

[p5pRT]

From wyp3rlx02@sneakemail.com

Hi,

Abigail abigail-at-abigail.be |newsgroups6| wrote​:

That will not pick up any lexical $_. It would if you'd used a '_' prototype​:

sub sqrt (_) {
my ($z) = @​_;
...

doh, of course. Thanks for catching that. If I recall correctly, the _
prototype can't be backported to 5.8 and earlier, right?

In any case, please disregard my patch.

Best regards,
Steffen

[p5pRT]

From @Abigail

On Fri, Jan 16, 2009 at 11​:33​:08AM +0100, Steffen Mueller wrote​:

Hi,

Abigail abigail-at-abigail.be |newsgroups6| wrote​:

That will not pick up any lexical $_. It would if you'd used a '_' prototype​:

sub sqrt (_) {
my ($z) = @​_;
...

doh, of course. Thanks for catching that. If I recall correctly, the _
prototype can't be backported to 5.8 and earlier, right?

Indeed. Both the '_' prototype and lexical $_ are new in 5.10.

Abigail

[p5pRT]

From @jhi

Abigail wrote​:

On Fri, Jan 16, 2009 at 11​:33​:08AM +0100, Steffen Mueller wrote​:

Hi,

Abigail abigail-at-abigail.be |newsgroups6| wrote​:

That will not pick up any lexical $_. It would if you'd used a '_' prototype​:

sub sqrt (_) {
my ($z) = @​_;
...
doh, of course. Thanks for catching that. If I recall correctly, the _
prototype can't be backported to 5.8 and earlier, right?

Indeed. Both the '_' prototype and lexical $_ are new in 5.10.

Which means without BEGIN + eval games that can't be in M​::C.

Abigail

[p5pRT]

From @nwc10

On Fri, Jan 16, 2009 at 07​:58​:00AM -0500, Jarkko Hietaniemi wrote​:

Abigail wrote​:

On Fri, Jan 16, 2009 at 11​:33​:08AM +0100, Steffen Mueller wrote​:

Hi,

Abigail abigail-at-abigail.be |newsgroups6| wrote​:

That will not pick up any lexical $_. It would if you'd used a '_' prototype​:

sub sqrt (_) {
my ($z) = @​_;
...
doh, of course. Thanks for catching that. If I recall correctly, the _
prototype can't be backported to 5.8 and earlier, right?

Indeed. Both the '_' prototype and lexical $_ are new in 5.10.

Which means without BEGIN + eval games that can't be in M​::C.

I don't think that an eval is needed - simply assign one of the alternatives
to *Math​::Complex​::sqrt

Or alternatively, a Corelist_pm.PL that has the two alternatives, and
Makefile.PL extracts.

(Hmm. Without XS, I can't see any way to change the prototype of a function
at run time.)

Nicholas Clark

[p5pRT]

From @rgs

2009/1/16 Nicholas Clark <nick@​ccl4.org>​:

On Fri, Jan 16, 2009 at 07​:58​:00AM -0500, Jarkko Hietaniemi wrote​:

Abigail wrote​:

On Fri, Jan 16, 2009 at 11​:33​:08AM +0100, Steffen Mueller wrote​:

Hi,

Abigail abigail-at-abigail.be |newsgroups6| wrote​:

That will not pick up any lexical $_. It would if you'd used a '_' prototype​:

sub sqrt (_) {
my ($z) = @​_;
...
doh, of course. Thanks for catching that. If I recall correctly, the _
prototype can't be backported to 5.8 and earlier, right?

Indeed. Both the '_' prototype and lexical $_ are new in 5.10.

Which means without BEGIN + eval games that can't be in M​::C.

I don't think that an eval is needed - simply assign one of the alternatives
to *Math​::Complex​::sqrt

Or alternatively, a Corelist_pm.PL that has the two alternatives, and
Makefile.PL extracts.

(Hmm. Without XS, I can't see any way to change the prototype of a function
at run time.)

Scalar​::Util​::set_prototype() ?

[p5pRT]

From @jhi

Steffen Mueller wrote​:

Hi Andrew, hi Jarkko,

the Porting/Maintainers.pl document in core now has a field that
indicates whether a given module considers CPAN or perl core 'upstream'.
It's not yet set for Math​::Complex. Please do set it so we know whether
to send patches to you or apply to core and let you pull them.

I would prefer the patches being sent to us (jhi or zefram).

The attached patch fixes a minor issue in Math​::Complex and adds a test.
It's a patch against the core Math​::Complex.

Best regards,
Steffen

[p5pRT]

From wyp3rlx02@sneakemail.com

Hi,

Jarkko Hietaniemi jhi-at-iki.fi |newsgroups6| wrote​:

Steffen Mueller wrote​:

the Porting/Maintainers.pl document in core now has a field that
indicates whether a given module considers CPAN or perl core 'upstream'.
It's not yet set for Math​::Complex. Please do set it so we know whether
to send patches to you or apply to core and let you pull them.

I would prefer the patches being sent to us (jhi or zefram).

Thanks for the info, I updated Porting/Maintainers.pl accordingly.

Best regards,
Steffen