*To*: mathgroup@smc.vnet.net*Subject*: [mg11028] ANNOUNCE: Math::ematica 1.105 - Perl talks to Mathematica talks to Perl*From*: Ulrich Pfeifer <pfeifer@wait.de>*Date*: Mon, 16 Feb 1998 18:15:32 -0500*Organization*: University of Dortmund, Germany*References*: <68n2lt$pm2@smc.vnet.net>

New in 1.105: Calling Perl from a running Mathematica session (calling back from a spawned sub-kernel was possible bevore). Ulrich Pfeifer -- NAME Math::ematica - Perl extension for connecting Mathematica(TM) SYNOPSIS use Math::ematica qw(:PACKET :TYPE :FUNC); WARNING This is alpha software. User visible changes can happen any time. The module is completely rewritten. Literally no line of the old stuff is used (don't ask - I've learned a few things since these days ;-). If you are using the old 1.006 version, note that the interface has changed. If there is an overwhelming outcry, I will provide some backward compatibility stuff. Feel free to suggest modifications and/or extensions. I don not use Mathematica for real work right now and may fail to foresee the most urgent needs. Even if you think that the interface is great, you are invited to complete the documentation (and fix grammos and typos). Since I am no native English speaker, I will delay the writing of real documentation until the API has stabilized. I do develop this module using Mathematica 3.0.1 on a Linux 2.0.30 box. Let me know, if it does work with other versions of Mathematica or does not work on other *nix flavors. DESCRIPTION The `Math::ematica' module provides an interface to the MathLink(TM) library. Functions are not exported and should be called as methods. Therefore the Perl names have the 'ML' prefix stripped. Since Perl can handle multiple return values, methods fetching elements from the link return the values instead of passing results in reference parameters. The representation of the data passed between Perl and Mathematica is straight forward exept the symbols which are represented as blessed scalars in Perl. Exported constants `PACKET' The `PACKET' tag identifies constants used as packet types. print "Got result packet" if $link->NextPacket == RETURNPKT; `TYPE' The `TYPE' tag identifies constants used as elements types. print "Got a symbol" if $link->GetNext == MLTKSYM; Exported functions `FUNC' The `FUNC' tag currently only contains the `symbol' function which returns the symbol for a given name. $sym = symbol 'Sin'; The plain interface This set of methods gives you direct access to the MathLink function. Don't despair if you don't know them too much. There is a convenient layer ontop of them ;-). Methods below are only commented if they do behave different than the corresponding C functions. Look in your MathLink manual for details. `new' The constructor is just a wrapper around `MLOpenArgv'. $ml = new Math::ematica '-linklaunch', '-linkname', 'math -mathlink'; The link is automatically activated on creation and will be closed upon destruction. `ErrorMessage' print $link->ErrorMessage; `EndPacket' `Flush' `NewPacket' `NextPacket' `Ready' `PutSymbol' `PutString' `PutInteger' `PutDouble' `PutFunction' `GetNext' `GetInteger' `GetDouble' `GetString' The method does the appropriate `MLDisownString' call for you. `GetSymbol' The module does the appropriate `MLDisownSymbol' call for you. It also blesses the result string into the package `Math::ematica::symbol'. `Function' Returns the function name and argument count in list context. In scalar contex only the function name is returned. `GetRealList' Returns the array of reals. The convenience interface `PutToken' Puts a single token according to the passed data type. $link->PutToken(1); # MLPutInteger Symbols are translated to `MLPutFunction' if the arity is provided as aditional parameter. $link->PutToken(symbol 'Pi'); # MLPutSymbol $link->PutToken(symbol 'Sin', 1); # MLPutFunction `read_packet' Reads the current packet and returns it as nested data structure. The implementaion is not complete. But any packet made up of `MLTKREAL', `MLTKINT', `MLTKSTR', `MLTKSYM', and `MLTKFUNC' should translate correctely. A function symbol `List' is dropped automatically. So the Mathematica expression `List[1,2,3]' translates to the Perl expression `[1,2,3]'. *Mabybe this is *too* convenient?*. `call' Call is the main convenience interface. You will be able to do most if not all using this call. Note that the syntax is nearly the same as you are used to as *FullForm* in Mathematica. Only the function names are moved inside the brackets and separated with ',' from the arguments. The method returns the nested data structures read by `read_packet'. $link->call([symbol 'Sin', 3.14159265358979/2]); # returns something near 1 To get a table of values use: $link->call([symbol 'Table', [symbol 'Sin', symbol 'x'], [symbol 'List', symbol 'x', 0, 1, 0.1]]); This returns a reference to an array of doubles. You may omit the first `symbol'. *Maybe we should choose the default mapping to *Symbol* an require *Strings*s to be marked?* `install' If you find this too ugly, you may `install' Mathematica functions as Perl functions using the `install' method. $link->install('Sin',1); $link->install('Pi'); $link->install('N',1); $link->install('Divide',2); Sin(Divide(Pi(),2.0)) # should return 1 (on machines which can # represent '2.0' *exactely* in a double ;-) The `install' method takes the name of the mathematica function, the number of arguments and optional the name of the Perl function as argument. $link->install('Sin',1,'sin_by_mathematica'); Make shure that you do not call any *installed* function after the `$link' has gone. Wild things will happen! `send_packet' Is the sending part of `call'. It translates the expressions passed to a Mathematica package and puts it on the link. `register' This method allows to register your Perl functions to Mathematica. *Registered* functions may be called during calculations. sub addtwo { $_[0]+$_[1]; } $link->register('AddTwo', \&addtwo, 'Integer', 'Integer'); $link->call([symbol 'AddTwo',12, 3]) # returns 15 You may register functions with unspecified argument types using undef: sub do_print { print @_; } $link->register('DoPrint', undef); $link->call(['DoPrint',12]); $link->call(['DoPrint',"Hello"]); `main' This method allows to have Perl scripts installed in a running Mathematica session. The Perl script try.pl might look like this: use Math::ematica; sub addtwo { my ($x, $y) = @_; $x + $y; } $ml->register('AddTwo', \&addtwo, 'Integer', 'Integer'); $ml->main; Inside the Mathematica do: Install["try.pl"] AddTwo[3,5]; Admittedly, adding two numbers would be easier inside Mathematica. But how about DNS lookups querying or SQL Databases? AUTHOR Ulrich Pfeifer <pfeifer@wait.de> SEE ALSO See also the perl(1) manpage and your Mathematica and MathLink documentation. Also check the t/*.t files in the distribution. ACKNOWLEDGEMENTS I wish to thank Jon Orwant of *The Perl Journal*, Nancy Blachman from *The Mathematica Journal* and Brett H. Barnhart from *Wolfram Research*. Jon brought the earlier versions of this module to the attention of Nancy Blachman. She in turn did contact Brett H. Barnhart who was so kind to provide a trial license which made this work possible. So subscribe to *The Perl Journal* and *The Mathematica Journal* if you are not subscribed already if you use this module (a Mathematica license is needed anyway). You would be nice to nice people and may even read something more about this module one day ;-) Special thanks to Randal L. Schwartz for naming this module. Copyright The Math:ematica module is Copyright (c) 1996,1997,1998 Ulrich Pfeifer. Germany. All rights reserved. You may distribute under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl README file. Mathematica and MathLink are registered trademarks of Wolfram Research.