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AG Numerik, Dynamik und Optimierung MAPLE Stochastic Package





The MAPLE Stochastic Package

by Sasha Cyganowski

Maintained by Lars Grüne

Extensions and Updates by
Thomas Pohl, Lars Grüne and Stefanie Schönbrodt




Contents:

    The MAPLE stochastic package offers a number of MAPLE routines for stochastic differential equations. The names of the functions are

      LO           SL0         LJ         MLJ               LFP
      itoformula   chainrule   correct    conv              explicit
      linearsde    reducible   colour     comm1             comm2
      linearize    momenteqn   position   sphere 
      
      Euler        Milstein    milcomm    Taylor1hlf        Taylor2
      wkeuler      wktay2      wktay3
      
      pa           ap          bpb        pmatrix2pvector   pvector2pmatrix
    


Downloading and Installation

We provide the stochastic package for Maple 6 --- 10 and for Maple V, Release 5.1.
  • For Maple 9 or newer, download the file stochastic9 (hold down shift when selecting the link or select "SaveAs" from the file menu after you have selected the link), and save it into some directory dir.

  • Type
    read "dir/stochastic9"; on UNIX/LINUX or Windows systems OR
    read "dir:stochastic9"; on Macintosh systems
    at the MAPLE prompt to load the file into MAPLE
    Caution:
    • On Macintosh computers it might be necessary to open the file in a text editor (e.g. BBedit) and save it under the same name as Simple Text
    • Some browsers, especially on Windows systems, automatically save the file under "stochastic9.html". Try
      read "dir/stochastic9.html"; if you encounter difficulties reading the package
    • On Windows systems the components of dir have to be seperated by "/" (not by "\" as usually)
    • On UNIX/LINUX you can omit dir/ when you start MAPLE from the directory dir

  • Type
    with(stochastic);
    at the MAPLE prompt to load the whole package.
    Alternatively, you can load single functions from the package typing
    with(stochastic, functionname);
    or access each function in the package using the long form
    stochastic[functionname];
    This might be necessary when there is a conflict between a package function name and another function used in the same session.


  • For Maple 6, 7, 8, proceed as above using the file stochastic6.
  • For Maple V, Release 5.1, proceed as above using the file stochastic5.


Recent Changes:

  • October 26, 2006: The package "stochastic9" and "stochplot9" were tested with Maple 10 and found to be working. If, however, you discover any problems, please let us know.

  • June 21, 2005: The new package "stochastic9" was placed here, which works with Maple 9 and 9.5.
    Many thanks to Stefanie Schönbrodt who analyzed the problem and made the necessary changes!

  • December 11, 2003: We fixed a bug in the itoformula-routine, which caused wrong results when the number of stochastic processes was larger than the dimension of the SDE.
    Many thanks to Björgvin Sigurdsson for reporting this error and providing a solution!

  • October 30, 2003: The new package "stochastic6" was placed here. Even though "stochastic5" runs without errors on Maple 6, 7 and 8 and produces correct output on the screen, some formulas give wrong results when used as an input to other Maple routines.
    Many thanks to Jerzy Ombach who corrected this problem!
We would also like to thank all the users who reported bugs and problems in older versions!

Documentation and Related Papers:


The stochplot package:

The "stochplot..."-files contain procedures for plotting approximate solutions curves for one-dimensional SDES. The output of any of the numerical scheme procedures from the stochastic package can be used as input. The corresponding demo worksheets demonstrate the use of these routines.

The source code for these packages can be loaded into a Maple worksheet using the read command as described above.


Recent Changes:

  • June 21, 2005: The package "stochplot9" and the related demo worksheet "stochplot9_demo.mw" were placed here. These are the same as the "6V3" versions except for the new "mw" format of the demo worksheet.

  • October 5, 2004: The package "stochplot6V3" and the related demo worksheet "stochplot6V3_demo.mws" were placed here. These files replace the "V2" versions and contain the new routine "stochplot_time" for time dependent one dimensional SDEs.

  • October 30, 2003: The package "stochplot6V2" and the related demo worksheet "stochplot6V2_demo.mws" were placed here. These files replace the old versions without version numbers and are compatible with the "stochastic6" package.

Note:

  • Since the stochplot packages are only suitable for 1d SDEs, they have a somewhat limited applicability and are mainly useful as templates for the development of more general routines. If you have written such routines and want to make them available to other users please contact me. I'll be happy to place them on this web site.

Additional Material:

The following files contain additional numerical schemes for SDEs. You should be familiar with the subject if you want to use them. No guarantee is given for the correctness of these algorithms, they are placed here as they may be of some benefit to others, but they are not part of the "stochastic" package.

The source code for these packages can be loaded into a Maple worksheet using the read command as described above.
  • moreschms (Explicit weak order 2 and implicit weak order 2 schemes)
  • weakimp2 (Implicit weak order 2 scheme)
  • wktay2 (Weak Taylor scheme of order 2)

Related Work:


Contact:

    Feel free to email us for comments:

      Lars Grüne (follow the link to see my e-mail address)
 

 Lars Grüne
 Last Change: October 26, 2006