[Bug fortran/32879] New: Document algorithm used for random generator

[Bug fortran/32879] New: Document algorithm used for random generator

[burnus at gcc dot gnu dot org]

gfortran has:
 irand() - g77
 rand() - g77
 random_number() - Fortran 90

The algorithm used is different.
Expected:
- State something about the used algorithm
- Point rand() users to random_number() as this algorithm is seemingly better.
  (or make at least clear(er) that the algorithms are different)

Cf. http://gcc.gnu.org/ml/fortran/2007-07/msg00454.html
> There are two random number generators in gfortran, one is a simple modulo 
> generator that is there for compatibility with g77, this is what you get when 
> you call RAND().
>
> The other is the RNG that implements the Fortran 90 RANDOM_NUMBER intrinsic. 
> [...] George Marsaglia's KISS (Keep It Simple Stupid)


-- 
           Summary: Document algorithm used for random generator
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Keywords: documentation
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32879

[Bug fortran/32879] Document algorithm used for random generator

[jb at gcc dot gnu dot org]

------- Comment #1 from jb at gcc dot gnu dot org  2007-07-24 16:30 -------
Confirmed, thought the documentation for RANDOM_NUMBER already mentions that it
uses KISS, so this applies only to the legacy intrinsics.


-- 

jb at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-07-24 16:30:19
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32879

[Bug fortran/32879] Document algorithm used for random generator

[burnus at gcc dot gnu dot org]

------- Comment #2 from burnus at gcc dot gnu dot org  2007-07-24 16:44 -------
> Confirmed, thought the documentation for RANDOM_NUMBER already mentions that it
> uses KISS, so this applies only to the legacy intrinsics.

Is KISS clear enough? If yes then it indeed only applies to RAND().

http://gcc.gnu.org/onlinedocs/gfortran/IRAND.html
http://gcc.gnu.org/onlinedocs/gfortran/RAND.html
http://gcc.gnu.org/onlinedocs/gfortran/RANDOM_005fNUMBER.html


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32879

[Bug fortran/32879] Document algorithm used for random generator

[patchapp at dberlin dot org]

------- Comment #3 from patchapp at dberlin dot org  2007-07-28 09:45 -------
Subject: Bug number PR32879

A patch for this bug has been added to the patch tracker.
The mailing list url for the patch is
http://gcc.gnu.org/ml/gcc-patches/2007-07/msg02029.html


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32879

[Bug fortran/32879] Document algorithm used for random generator

[dfranke at gcc dot gnu dot org]

------- Comment #4 from dfranke at gcc dot gnu dot org  2007-07-29 10:01 -------
Subject: Bug 32879

Author: dfranke
Date: Sun Jul 29 10:01:27 2007
New Revision: 127037

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=127037
Log:
2007-07-29  Daniel Franke  <franke.daniel@gmail.com>

        PR fortran/32879
        * intrinsic.texi (IRAND, RAND, RANDOM_NUMBER): Document algorithm
        used for random number generator.


Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/intrinsic.texi


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32879

[Bug fortran/32879] Document algorithm used for random generator

[dfranke at gcc dot gnu dot org]

------- Comment #5 from dfranke at gcc dot gnu dot org  2007-07-29 10:49 -------
Subject: Bug 32879

Author: dfranke
Date: Sun Jul 29 10:49:11 2007
New Revision: 127042

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=127042
Log:
2007-07-29  Daniel Franke  <franke.daniel@gmail.com>

        Backport from trunk:
        2007-07-29  Daniel Franke  <franke.daniel@gmail.com>
        * invoke.texi: Removed -w from option summary.

        2007-07-29  Daniel Franke  <franke.daniel@gmail.com>
        PR fortran/32879
        * intrinsic.texi (IRAND, RAND, RANDOM_NUMBER): Document
        algorithm used for random number generator.

        2007-07-13  Daniel Franke  <franke.daniel@gmail.com>
        * invoke.texi: Unified upper- and lower-case in menus.
        (-w, -W): Removed, documented by gcc.
        * intrinsic.texi: Unified Class-section entries, added
        subroutine/function warning where appropiate.

        2007-05-01  Daniel Franke  <franke.daniel@gmail.com>
        * intrinsic.texi (MVBITS): Changed class to elemental subroutine.
        (RANDOM_NUMBER): Changed class to subroutine.
        (HUGE, TINY): Changed class to inquiry function.


Modified:
    branches/gcc-4_2-branch/gcc/fortran/ChangeLog
    branches/gcc-4_2-branch/gcc/fortran/intrinsic.texi
    branches/gcc-4_2-branch/gcc/fortran/invoke.texi


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32879

[Bug fortran/32879] Document algorithm used for random generator

[dfranke at gcc dot gnu dot org]

------- Comment #6 from dfranke at gcc dot gnu dot org  2007-07-29 10:50 -------
Documented in 4.2 and trunk. Closing.


-- 

dfranke at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dfranke at gcc dot gnu dot
                   |                            |org
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32879