Fantastic idea - We also develop scheduling solutions and I have considered this implementation myself (and ODBC which you have already done) but never had the opportunity to implement it.
Well done. Regards, Harley Mackenzie xypron wrote: > Hello Andrew, > > currently I am using GLPK mainly for scheduling problems. Here the data > often contains references to time. The GMPL language does not provide any > functions to convert timestamps to numbers and numbers back to timestamps. > > I propose to add the following functions: > > now() returns the number of seconds since 1970 > Knowing the current time is useful as scheduling should not place production > in the past. > > str2time( str, fmt ) converts a timestamp str given in format fmt to number > of seconds since 1970 > e.g. str2time( "2008-11-15T13:22:10+0300", "%Y-%m-%dT%H:%M:%S%z"); > The time formats of RFC 3339 should be supported (a subset of ISO 8601). > The format strings should be a subset of those used by the strptime() > function in library GLIBC. > Conversion of non local time will have to rely on availability of either > function timegm() (or _mkgmtime for Microsoft Visual C) or structure element > tm->tm_gmtoff. > > localtime( num, fmt ) converts a number to a timestamp in local time > e.g. localtime( now(), "%Y-%m-%dT%H:%M:%S%") > a possible output would be > 2008-11-15T17:22:10 > The format strings should be those used by the strftime() function in C99. > > gmtime( num, fmt ) converts a number to a timestamp in global time > e.g. gmtime( now(), "%Y-%m-%dT%H:%M:%S%Z") > a possibel output would be > 2008-11-15T16:22:10 > The format strings should be those used by the strftime() function in C99. > > I have implemented the necessary changes to glpk-4.33 which can be found at > http://glpk.dyndns.org/viewvc/svn/glpk/glpk/branches/glpk-4.33-strdate/ > http://glpk.dyndns.org/viewvc/svn/glpk/glpk/branches/glpk-4.33-strdate/ > > new files are: > include/glptime.h > src/glptime.c > > changed files are: > configure.ac > config.h.in > include/glpmpl.h > src/Makefile.am > src/glpmpl01.c > src/glpmpl03.c > w32/Makefile* > w32/config_VC9 > w64/Makefile* > w64/config_VC9 > > Best regards > > Xypron > > -- ------------------------------------------------------------------ Dr. Harley Mackenzie ABN: 36 348 783 012 HARD Software Web: www.hardsoftware.com PO BOX 8004 Tel: +61 3 5222 3435 Newtown 3220, Australia Email: [EMAIL PROTECTED] ------------------------------------------------------------------ _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
