Internet Info 1993

home *** CD-ROM | disk | FTP | other *** search

/ Internet Info 1993 / Internet Info CD-ROM (Walnut Creek) (1993).iso / answers / comp / matlab-faq < prev next >

Wrap

Internet Message Format | 1993-11-24 | 35.5 KB

Path: senator-bedfellow.mit.edu!bloom-beacon.mit.edu!gatech!swrinde!elroy.jpl.nasa.gov!netline-fddi.jpl.nasa.gov!csi.jpl.nasa.gov!nobody From: mwette@mr-ed.jpl.nasa.gov (Matt Wette) Newsgroups: comp.soft-sys.matlab,comp.answers,news.answers Subject: comp.soft-sys.matlab FAQ (Frequently Asked Questions) Followup-To: comp.soft-sys.matlab Date: 23 Nov 1993 09:31:34 -0800 Organization: Jet Propulsion Laboratory Lines: 937 Approved: news-answers-request@MIT.Edu Message-ID: <2cthdm$40v@mr-ed.jpl.nasa.gov> Reply-To: mwette@csi.jpl.nasa.gov NNTP-Posting-Host: mr-ed.jpl.nasa.gov Summary: This article includes product notes and answers to frequently asked user questions about the matrix-oriented environment MATLAB, by The MathWorks, and products and tools based on or related to MATLAB. Xref: senator-bedfellow.mit.edu comp.soft-sys.matlab:3103 comp.answers:2776 news.answers:15030 Archive-name: matlab-faq Last-modified: 1993/11/23 Version: $Id: FAQ.in,v 1.2 1993/11/23 17:24:16 mwette Exp $ This FAQ is maintained by Matt Wette <mwette@csi.jpl.nasa.gov>. The latest version can be retrieved via anonymous ftp from csi.jpl.nasa.gov [128.149.29.4] as /pub/matlab/FAQ.text (plain text) or /pub/matlab/FAQ.html (HTML format) Contributions, corrections and suggestions are welcomed. Last update: Tue Nov 23 09:26:35 PST 1993 MATLAB Frequently Asked Questions ================================= SYNOPSIS General ======= 1) What is MATLAB? 2) What is the charter for the comp.soft-sys.matlab group? 3) What commercially available MATLAB-type environments are sold? 4) What non-commercial MATLAB-type environments exist? 5) Are there any standards for MATLAB-type tools? 6) How can I join a MATLAB user group? 7) Are there any software archives? 8) Are there any publications related to MATLAB? MATLAB/SIMULINK Product Information =================================== 9) What's new in MATLAB 4.0? 10) How does MATLAB perform on machine X? 11) What is SIMULINK (alias Simulab)? 12) What toolboxes are currently available from The MathWorks? 13) Can I use C and Fortran programs with MATLAB? 14) How do I contact The MathWorks about MATLAB via email? MATLAB User Questions ===================== 15) How can I change the default window size, colors, etc. in MATLAB 4? 16) How can I import MATLAB graphics into my Framemaker, TeX, etc. document? 17) Is there a topical help function, like `apropos'? 18) Why am I finding all these undocumented functions (like COMET) in MATLAB? 19) Has anybody any information about the matlab function `system_dependent'? 20) How can I get the parser to accept a dummy reference without an error? 21) How do I get the plot command to cycle through line-types? 22) Can I use `dbup' and `dbdown' within a function? 23) Is there a GNU emacs editing mode for MATLAB? 24) What is the sign convention used in MATLAB's FFT routines? 25) Is there any MATLAB software for wavelets? 26) Is there any MATLAB software for fuzzy logic? 27) Is there any MATLAB software for communications? 28) Is there a MATLAB interface to Mathematica? 29) Why was `fsolve' removed from MATLAB Version 4? 30) Are there any published books on, or relating to, MATLAB? Quick Little MATLAB Hacks ========================= 31) How can I initialize a this low rank matrix easily? 32) How can I load-from or save-to a file whose name is in a string variable? 33) How can I store the result of `!ls *.dat' in a variable? 34) How can I make a variable global from within a function? MATLAB on the PC ================ 35) What can I do when MATLAB tells me there is not enough environment space? Xmath / MatrixX Product Information. ==================================== 36) What is Xmath? 37) Are there any publications related to MatrixX? 38) Are there any e-mail addresses related to MatrixX/Xmath? 39) What other modules are available from ISI? Xmath User Questions ==================== 40) Is it possible to derive new classes in XMath? General ======= 1) What is MATLAB? MATLAB is the name used to refer to the class of matrix cal- culator environments derived from the first, called MATLAB. MATLAB was developed by Cleve Moler in the late 1970s at the University of New Mexico and other locations with support from the National Science Foundation. Since then, many work-a-likes have been developed or are in development com- mercially, in government and university labs, and so forth. The name of the product available from MathWorks is "MATLAB", not Matlab, Pro-MatLab, etc. Note that MathWorks holds a registered trademark on the uppercase version of MATLAB. In this document, Matlab may refer to the collective set of MATLAB-based environments or it may refer to the current im- plementation developed by MathWorks, Inc. In general, these MATLAB-based environments are not source-language compati- ble. 2) What is the charter for the comp.soft-sys.matlab group? The newsgroup 'comp.soft-sys.matlab' is a forum for discuss- ing issues related to the use of MATLAB, the scientific cal- culation and visualization package from MathWorks Inc. This includes discussion of similar software packages which are also derived from the original `Classic MATLAB', such as Xmath from Integrated Systems Inc. Appropriate discussion in the group will include both gen- eral Matlab issues and platform-specific questions, and dis- cussion comparing MATLAB to other systems. 3) What commercially available MATLAB-type environments are sold? In alphabetical order: `CLAM' from Scientific Computing Associates, Inc. 246 Church Street, Suite 307 New Haven, CT 06510 Tel: 203-777-7442 Fax: 203-776-4074 `Ctrl-C' from Systems Control Technology, Inc. CAE Systems Department 2300 Geng Road Palo Alto, CA 94303 Tel: 800-227-1910 Tel: 415-494-2233 Fax: 415-496-6595 `MATLAB' from The MathWorks, Inc. Cochituate Place 24 Prime Park Way Natick, MA 01760 Tel: 508-653-1415 Fax: 508-653-2997. Email: info@mathworks.com `O-MATRIX' from Harmonic Software, Inc. 12223 Dayton Avenue North Seattle, WA 98133 Tel: 206-367-8742 Fax: 206-367-1067 Email: harmonic@world.std.com `Xmath' from Integrated Systems, Inc. 3260 Jay St. Santa Clara, CA 95054-3309 Tel: (408) 980-1500 Fax: (408) 980-0400 Email: xmath-info@isi.com 4) What non-commercial MATLAB-type environments exist? In alphabetical order: `Caesy' is being developed by Matt Wette (mwette@csi.jpl.nasa.gov) at the Jet Propulsion Laboratory. This will be released to COSMIC soon. It will provide data structures, conversion to C-code, and many other features. See M.Wette, "Caesy: A Computer-Aided Engineering System" Proc. 1992 Symp. on Computer-Aided Control System Design Napa, CA, March 1992 `Mat/C' developed at Lawrence Livermore National Labora- tories by Don Gavel. This is not publically available. `Matcalc', by M.Gerberg and E.J. Moore, University of New South Wales, Australia. It is available via anonymous ftp from draci.cs.uow.edu.au in /netlib/matcalc/ csi.jpl.nasa.gov in /pub/matlab/matcalc/ `MaTX', an interpreter and compiler, developed at Tokyo In- stitute of Technology. See M. Koga and K. Furuta, "MaTX: A High-Performance Programming Language (Interpreter and Compiler) for Scientific and Engineering Computation," Proc. 1992 Symp. on Computer-Aided Control System Design, Napa, CA, March 1992 `MEDAL' developed at the University of Waterloo by Grantham Pang (pang@excel2.uwaterloo.ca). This has the same command language as MATLAB, but includes a knowledge-based expert system development facility. It is available for academic and research users via anonymous. You'll need to get a pro- gram password from the author to operate it (no sources in- cluded). It's available via anonymous ftp from excel2.uwaterloo.ca [129.97.86.13] in /pub/ See Pang, G.K.H.,"Knowledge-based Control System Design", in Recent Advances in Computer-Aided Control Systems Engineering, Jamshidi, M and Herget, C.J. (ed.), Elsevier Science Publishers, 1992. Pang, G.K.H., "A Knowledge Environment for an Interactive Control System Design Package", Automatica, Vol. 28. No. 3, pp. 473-491, May 1992. `Octave', written at the University of Texas (jwe@che.utexas.edu), is available via anonymous ftp from ftp.che.utexas.edu as /pub/octave/octave-?.?.tar.Z `RLaB', written by Ian Searle (ians@eskimo.com), is free software (in the GNU copyleft sense). It is currently available via anonymous ftp from csi.jpl.nasa.gov in /pub/matlab/RLaB evans.ee.adfa.oz.au in /pub/RLaB 5) Are there any standards for MATLAB-type tools? There is an IFAC/IEEE-CSS Working Group developing standards and guidelines for these tools. A proposed standard command language was developed, is described in the document "Com- mand Language Standard for CACSD Software" and is available from Magnus Rimvall Control Systems Laboratory, GE-CRD Schenectady, NY 12301 6) How can I join a MATLAB user group? To join the user group, send your name, affiliation and ad- dress to: matlab-users-request@mcs.anl.gov For European user groups, contact: France: Alain Baron phone: 33/1 45 34 23 91 fax: 33/1 45 07 08 06 Germany: Dr. Ingrid Bausch-Gall phone: 49/89 323 2625 fax: 49/89 323 1063 Sweden: Svante Littmarck phone: 46/8 15 30 22 fax: 48/8 15 76 35 email: info@comsol.se Switzerland: Carl Bergstrom phone: 031/961 70 11 fax: 031/961 12 82 email: comsol@clients.switch.ch UK: Peter Campbell phone: +44-223-421920 fax: +44-223-421921 7) Are there any software archives? Yes. MATLAB User Group software archive contains more than 1MB of user-contributed code. This archive is located on NETLIB server of Oak Ridge National Laboratories. To learn more, send following message: send index send index from matlab to: netlib@ornl.gov For access from Europe, try the duplicate collection in Oslo: Internet: netlib@nac.no EARN/BITNET: netlib%nac.no@norunix.bitnet X.400: s=netlib; o=nac; c=no; EUNET/uucp: nac!netlib For the Pacific, try netlib@draci.cs.uow.edu.au located at the University of Wollongong, NSW, Australia. The MathWorks maintains the archive on the anonymous ftp server ftp.mathworks.com [144.212.100.10]. This site con- tains a "best of" copy of the NETLIB archive as well as oth- er user-contributed, and MathWorks contributed software and documentation. If you are interested in submitting software to the archive pick up the file README.incoming from the ar- chive or send e-mail to drea@mathworks.com There is a renegade archive at csi.jpl.nasa.gov [128.149.29.4], in /pub/matlab. This is stocked with a mish-mash of stuff you may not find on the other archives (e.g., free MATLAB-look-a-likes). 8) Are there any publications related to MATLAB? Yes, Math Works Inc. publishes a quarterly magazine called MathWorks Newsletter, giving info. on products (new ver- sions, releases, toolboxes), matlab user group, matlab short courses, related texts etc. To subscribe to the newsletter, send email with your snail mail address to subscribe@mathworks.com. MATLAB/SIMULINK Product Information =================================== 9) What's new in MATLAB 4.0? from John Little ... Here's the "high-level" summary of the major new additions: * Object-based graphics facility * 3-D color scientific visualization abilities * Animation * Sound output capability * M-file debugging facilities * Low-level file I/O functions * Graphical user interface controls (GUI widget set) * Sparse matrix support * An improved help system * Interpreter and graphics speed improvements * A new External Interface library (MEX-files, engine, MAT-files) * Better documentation (in the eyes of the beholder, I imagine :-) ) * Lots of other smaller improvements.. 10) How does MATLAB perform on machine X? LINPACK benchmarks in MATLAB (reported by The MathWorks): machine KFLOPS (LINPACK) ======= ================ Macintosh (8MHz 68000) 3 PC/AT (6.0MHz/80286/EGA) 15 PC/XT (4.7MHz/8088/CGA) 17 AT&T 6300 (8MHz/8086) 29 Macintosh II (68020/68881) 85 MicroVAX II (VMS/D_floating) 140 Macintosh IIcx (68030/68882) 168 HP 9000/Series 350 190 80386/80387 (20MHz, 386-MATLAB) 232 Macintosh IIci (25MHz 68030/68882) 239 VAXstation 3100 (VMS/D_floating) 365 HP 9000/400 (68030) 500 80486-based PC (33M Hz) 1300 HP 9000/425 (68040 chip) 1400 Macintosh Quadra 700 1500 Sun SPARCstation 1 1500 DECstation 3100 1600 SGI Indigo 2400 Sun SPARCstation 2 2900 Convex C1 3700 IBM RS/6000 7000 HP 9000/700 7400 Cray X-MP 71000 Cray X-MP on a 500-by-500 matrix 135000 Other numbers (reported by users): 80486-DX2 PC @66MHz 3121 (k.hari@ieee.org) 11) What is SIMULINK (alias Simulab)? SIMULINK is an interactive system for the nonlinear simula- tion of dynamical systems. It is a graphical, mouse-driven program that allows systems to be modelled by drawing a block diagram on the screen. It can handle linear, non- linear, continuous-time, discrete-time, multivariable, and multirate systems. SIMULINK runs on workstations using X- windows, under MicroSoft Windows on the PC, and on the Ma- cintosh. It takes full advantage of windowing technology, including pull-down windows and mouse interactions. SIMULINK is fully integrated with MATLAB, and, together with MATLAB and the Control System Toolbox, forms a complete control system design and analysis environment. 12) What toolboxes are currently available from The MathWorks? The following list includes toolboxes currently offered by The MathWorks. For more info check ftp.mathworks.com in /pub/product-info Signal Processing Toolbox. This is a toolbox for digital signal processing (time series analysis). It includes functions for the design and analysis of digital filters, like Butterworth, Elliptic, and Parks-McClellan, and for FFT analysis (power spectrum esti- mation). It also includes some 2-dimensional signal pro- cessing capabilities. Control System Toolbox. This is a toolbox for control system design and analysis. It supports transfer function and state-space forms (continuous/discrete time, frequency domain). Function for step, impulse, arbitrary input responses, as well as Bode, Nyquist, and Nichols plots. Design with root-locus, pole- placement, and LQR optimal control. System Identification Toolbox. This is a toolbox for parametric modelling. Identified models are in transfer function form (either z-transform or Laplace transform) and state-space form (e.g., ARMA models or Box-Jenkins models). Optimization Toolbox. This is a toolbox for linear and nonlinear optimization and supports unconstrained and constrained minimization, minimax, nonlinear least squares, multi-objective, and semi-infinite optimization, linear programming, quadratic programming and the solution of non-linear equations. Spline Toolbox. This is a toolbox for working with splines and is typically used for curve fitting, solution of function equations and functional approximation. Robust-Control Toolbox. This is a toolbox for robust control system design and sup- ports LQG/loop transfer recovery, H2, H0, and mu- control synthesis, singular value frequency response, and model reduction. Neural Net Toolbox. This is a toolbox for designing and simulating neural net- works and supports implementation of the perceptron learning rule, the Widrow-Hoff rule, and several variations of the backpropagation rule. Transfer functions included are hard limit, linear, logistic & hypertangent sigmoid. Delta Toolbox. This is a toolbox for analysis using the delta transform, an approach to unifying continuous and discrete systems theory without use of the Z-transform. It is available free to purchasers of "Digital Control and Estimation: A Unified Ap- proach," by Graham Goodwin and Rick Middleton. Image Processing Toolbox. The Image Processing Toolbox provides an environment for im- age processing and analysis. Images are matrices (surprised?). Functions include linear and nonlinear filtering; image restoration; image enhancement; image analysis and statistics; color, geometric, and morphological operations 2-D transforms; and 2D FIR filter design and fre- quency response. Symbolic Math Toolbox. The Symbolic Math Toolbox contains functions for symbolic algebra, exact linear algebra, variable precision arithmet- ic, equation solving, and special mathematical functions. Its underlying computational engine is the kernel of Maple. The Extended Symbolic Math Toolbox augments the functionali- ty to include Maple programming features and specialized li- braries. Statistics Toolbox. The Statistics Toolbox provides statistical data analysis, modeling, and Monte Carlo simulation; building-blocks for creating your own special-purpose statistical tools; and GUI tools for exploring fundamental concepts in statistics and probability. Functionality covers descriptive, inferential, and graphical statistics, and linear models as well as in- teractive graphics for dynamic visualization of functions, data, and probability distributions. 13) Can I use C and Fortran programs with MATLAB? MATLAB's MEX-file facility allows user to use C and Fortran subroutines as MATLAB m-files. It is also possible to use MATLAB as a computational engine for C/Fortran subroutines. 14) How do I contact The MathWorks about MATLAB via email? Here you go ... * support@mathworks.com technical support * suggest@mathworks.com product enhancement suggestions * bugs@mathworks.com bug reports * doc@mathworks.com documentation error reports * register@mathworks.com user and product registration * subscribe@mathworks.com subscribing user registration * info@mathworks.com sales, pricing, general info. * netlib@ornl.gov software archive contact * digest@mcs.anl.gov user group MATLAB User Questions ===================== 15) How can I change the default window size, colors, etc. in MATLAB 4? from serr15@liverpool.ac.uk ... Try something like the following in your `startup.m' file: set(0,'DefaultFigurePosition',[5 5 505 405]) set(0,'DefaultFigureColor',[0,0,0]) %% N.B this has side effects. set(0,'DefaultAxesFontName','times') set(0,'DefaultTextFontName','times') set(0,'DefaultAxesFontSize',12) set(0,'DefaultTextFontSize',12) 16) How can I import MATLAB graphics into my Framemaker, TeX, etc. document? The MATLAB (version 4) print command provides a "-deps" ar- gument which provides a Encapsulated PostScript file of your plot. Some people have reported various problems getting this stuff to work. Some suggestions: Removing the last line "%%EOF" from the eps-file. Use the the pstoepsi filter from Doug Crabill (dgc@cs.purdue.edu). Use "bbps" and ghostscript. "bbps.shar" is available via anonymous ftp on "csi.jpl.nasa.gov". You'll need to get GhostScript from your nearest GNU ftp site. [This area needs more work :). ed.] 17) Is there a topical help function, like `apropos'? Yes. The function you're looking for is `lookfor' (in MATLAB 4). >> lookfor fourier FFT Discrete Fourier transform. FFT2 Two-dimensional Fast Fourier Transform. IFFT Inverse discrete Fourier transform. IFFT2 Two-dimensional inverse discrete Fourier transform. FOURIER Graphics demo of Fourier series expansion. DFTMTX Discrete Fourier transform matrix. >> 18) Why am I finding all these undocumented functions (like COMET) in MATLAB? from Cleve Moler ... Almost everything in the "demos" directory is not described in the User's Guide. There are lots of goodies there. In 4.0, the demos are best place to see examples of Handle Graphics. There are other undocumented functions in directories other than demos. Some of them are "worker" functions that are unlikely to be used directly; they are simply called by oth- er functions. A few, like COMET and COMET3, were actually written after the User's Guide had been sent to the printer. 19) Has anybody any information about the matlab function `system_dependent'? from John Little (w/editing) ... `system_dependent' is an unpublished function that is used for a variety of crufty things. It will most certainly change from time to time and possible even go away complete- ly. For anybody curious about it, here is what it does in MATLAB 4.0 on SPARCstations: system_dependent(1) deals with the MATLAB-ACSL interface. ACSL is a simulation language that MATLAB can talk to. See ACSL.M for more information. system_dependent(2,0) turns off command-line editing. system_dependent(2,1) turns it back on. system_dependent(3) is unused. system_dependent(4,i,j) is used to program the command-line editing keys. See CEDIT.M for more information. system_dependent(5) enables core dumps in the event of seg faults. Normally MATLAB tries to catch seg faults and "continue". system_dependent does different things in MATLAB 3.5 and other platforms. 20) How can I get the parser to accept a dummy reference without an error? Adopted from post by Jim Tung ... MATLAB parses code to look for syntax errors. When the parser encounters a name with 2 or fewer arguments, it lets them pass since they might be a variable with indices. If it encounters a name with 3 or more arguments, MATLAB knows it cannot be a variable, so the error message is returned. If you don't want the parser to snag the function, specify one with 2 or fewer arguments. 21) How do I get the plot command to cycle through line-types? From Chuck Packard <cpackard@mathworks.com> ... MATLAB v4.1 has a an axis property LineStyleOrder for this. Monochrome users can tell MATLAB to always use white lines and cycle through their favorite line styles with the com- mands: set( 0, 'DefaultAxesColorOrder', [1 1 1] ) set( 0, 'DefaultAxesLineStyleOrder', '-|:|--' ) These commands can be put in your startup.m to always give you styled lines. 22) Can I use `dbup' and `dbdown' within a function? Derived from post's of lara@mrisun.med.yale.edu and jlittle@mathworks.com ... MATLAB wasn't designed to be used this way. But, if you don't reference any variables between your calls to `dbup' and `dbdown' (i.e., you just use `save', `who', `dir', etc), it should work. Otherwise, you may well run into problems. If you `dbup' while in a function, you change the workspace context while continuing execution of the original function. This means that subsequent references to variables will be bound to variables in a different workspace. Since the internal p-code uses integers as variable identifiers, you will get a random attachment to these different variables. At best, you'll get random results. At worst you might seg fault if you exceed the number of available identifiers. 23) Is there a GNU emacs editing mode for MATLAB? A GNU emacs `matlab-mode' is available via anonymous ftp from csi.jpl.nasa.gov as pub/matlab/util/matlab-mode.el 24) What is the sign convention used in MATLAB's FFT routines? The FFT in MATLAB is defined as sum(x(i)*exp(-j*i*k/N)) and not sum(x(i)*exp(j*i*k/N)). The first version is tradition- ally used by engineers, the second version by mathemati- cians. Since MATLAB was written by an engineer (John Lit- tle), the engineering approach was used. 25) Is there any MATLAB software for wavelets? Contact Carl Taswell <taswell@sccm.stanford.edu> is working on a wavelet toolbox. The toolbox and associated papers are available via anonymous ftp from simplicity.stanford.edu in /pub/taswell A newer version should be available soon. Also, Jeff Kantor <jeffrey.kantor@nd.edu> is distributing a wavelet toolbox. It is available via anonymous ftp from control.cheg.nd.edu in /pub/wavelets/wavetools1_1.tar The toolbox, rice-wlet-tools-1.1, a collection of MATLAB "mfiles" and "mex" files for twoband and M-band filter bank/wavelet analysis, is available via anonymous ftp from cml.rice.edu in /pub/dsp/{software,papers} Contact Ramesh Gopinath <ramesh@dsp.rice.edu>. 26) Is there any MATLAB software for fuzzy logic? A.Lotfi <lotfia@s1.elec.uq.oz.au> has developed a Fuzzy Inference Systems Toolbox. It is available via anonymous ftp from ftp.mathworks.com as /pub/contrib/misc/fuzzy_inference_systems.sh or /pub/contrib/misc/pc_fuzzy_inference_systems.sh A Fuzzy-Control Toolbox has been developed by Bernhard Kaemmpf <kaempf@ifr.luftfahrt.uni-stuttgart.de>. Send him email if you are interested in obtaining the software. (Sounds like he is willing to give it away.) Jyh-Shing Roger Jang <jang@diva.berkeley.edu> has provided a few routines for demonstrating parameterizing membership functions (MF) and learning in fuzzy inference systems (FIS). The file fuzzdemo.tar.Z is available via anonymous ftp from csi.jpl.nasa.gov in /pub/matlab/contrib/ 27) Is there any MATLAB software for communications? Mehmet Zeytinoglu <mzeytin@ee.ryerson.ca> has written a MATLAB toolbox for communications. It is available via anonymous ftp from ftp.mathworks.com as /pub/contrib/misc/comm_tbx.tar 28) Is there a MATLAB interface to Mathematica? Yes. WRI has developed a free MATLAB-Mathematica interface. It is available via anonymous ftp from mathsource.wri.com as /pub/WhatsNew/matlab2math.tar.Z (Unix) or /pub/WhatsNew/matlab2math.sea.hqx (Mac) or /pub/WhatsNew/matlab2math.zip (Windows) ? or via email via "send 0205-951" to mathsource@wri.com. 29) Why was `fsolve' removed from MATLAB Version 4? The algorithms used by fsolve were not numerically well behaved. MathWorks did not feel that it met the standards require for approved software. The version of FSOLVE in the Optimization Toolbox is recommended. If your site doesn't still have the 3.5 version, you can get it via anonymous ftp from ftp.mathworks.com as /pub/contrib/optim/fsolve35.tar 30) Are there any published books on, or relating to, MATLAB? There is a list of published book available via anonymous ftp from csi.jpl.nasa.gov as /pub/matlab/matlab-books Quick Little MATLAB Hacks ========================= 31) How can I initialize a this low rank matrix easily? Here's "Tony's trick", attributed to Tony Booer of Schlum- berger: To initialize a matrix with values "a" in the first row and values "b" in the second row, do the following: [a(1,ones(1,m)) ; b(1,ones(1,m))] 32) How can I load-from or save-to a file whose name is in a string variable? name = 'xyz.mat'; eval(['save ', name]); eval(['load ', name]); 33) How can I store the result of `!ls *.dat' in a variable? [stat, list] = unix('ls *.dat'); The variable `stat' contains the return status, the variable `list' contains the output. 34) How can I make a variable global from within a function? You can in MATLAB 4. The following hack is from Laura Nee- dles <lohrah@csi.jpl.nasa.gov> and Mike Kantner <rainbow@csi.jpl.nasa.gov>. Define the script file `mkglobal.m', containing function [] = mkglobal(var) % MKGLOBAL mkglobal(var) - make var a global variable if ~exist('mkglobal_var'), mkglobal_1; end; mkglobal_var = var; mkglobal_2 Define the script file `mkglobal_1.m' as global mkglobal_var Define the script file `mkglobal_2.m' as eval(['global ', mkglobal_var]); MATLAB on the PC ================ 35) What can I do when MATLAB tells me there is not enough environment space? This usually happens if in the matlab path you include greater that 4 or 5 paths. One solution is to increase your environment space by adding the following command in your config.sys file: shell=c:\dos\command.com /e:nnnnn /p where nnnnn is the number of bytes you use for environment memory. It varies from 256 bytes to 32768 bytes(32Kbytes). Usually, 5000 bytes can solve your problem. (The /p command is used so that the autoexec.bat file runs when you boot your computer.) Xmath / MatrixX Product Information. ==================================== 36) What is Xmath? from mesaros@isi.com ... Xmath is an interactive mathematics, scripting, and graphics environment for X Window workstations. It has features which represent a significant improvement on matlab-type software tools, including: * Object-oriented scripting language. * "Point-and-click" color graphics. * Visual debugging tool. * LNX and C-callable libraries. * Programmable MOTIF GUI layer. Xmath from Integrated Systems Inc. is available on the In- ternet via FTP from isi.com. If you would like to down-load Xmath to view the Xmath Interactive demo, do the following: From the UNIX/Shell environment, type: ftp isi.com (if the host is unknown, try ftp 192.73.222.1) When asked for name/user, type: anonymous When asked for the password, simply type your e-mail address. Once your e-mail address is accepted, and if the maximum number of ftp clients has not been exceeded, the connection will be made and a list of instructions will appear. Simply follow that list of instructions to transfer a copy of Xmath to your system. 37) Are there any publications related to MatrixX? Yes, ISI publishes a quarterly magazine called Response Times that gives information on products (new ver- sions, releases, modules), user conference, classes, and a Techni- cal Support Corner where they answer user questions. Also, ISI has an annual Users Conference. The viewgraph presentations from this conference are available. The next conference in March 15-17, 1993. 38) Are there any e-mail addresses related to MatrixX/Xmath? Yes. Some are: * support@isi.com tech support for ISI MatrixX products (408)980-1590 ext. 321 * info@isi.com product literature requests * kate@isi.com contributions to Response Times Mag 39) What other modules are available from ISI? * MatrixX/XMath * Robust Control Module * Optimization Module * Model Reduction Module * Digital Signal Processing Module * System Identification Module * System_Build * RT/Expert System Block * RT/Fuzzy Logic Block * Interactive Animation * AutoCode (C,FORTRAN, Ada) * Automatic Documentation Generation 3rd Party Packages * ADAPTx Automated System Identification Software Real Time Execution * AC-100 Product for Hardware in the Loop Simulations ISI recently merge with the Software Component Group that makes and sells the PSOS+ real time operating system and development tools. Xmath User Questions ==================== 40) Is it possible to derive new classes in XMath? From Alexandra Schmidt <aliki@isi.com> ... Xmath does not currently allow you to 'derive' new subc- lasses from the built-in ones (dynamic systems, parameter- dependent matrices, strings and string matrices, polynomi- als, "special matrices", etc.) However, a number of our users have used the list object to create compound objects containing different kinds of built-in objects, then used the resulting list-based object for more complex data model- ing. Your question echoes a request we've heard a number of times and is a high priority for our future development, so keep an eye out. . . $Id: FAQ.in,v 1.2 1993/11/23 17:24:16 mwette Exp $