installation.html

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are shipped with QMG.  But you may use your system's built-in
Lapack/BLAS or just BLAS alone, which may be more efficient.  In this
case, you should customize the file named <code>custom</code> according
to the instructions in that file.

<h3>Special note for Visual C++ users</h3>
It
is recommended that you update
the standard header files for Visual C++ 5.0 according to the 
<a href="http://www.dinkumware.com/vc_fixes.html">Dinkumware 
website</a> 
before compiling QMG.  This fixes many bugs in the versions
of the standard headers shipped with VC++ 5.0. 
It is not clear whether
these bugs are fixed in VC++ 6.0.

<p>
In addition, there is one more patch that is not reported
on the Dinkumware website.  The following
code using standard class <code>ostringstream</code>
requires O(n<sup>2</sup>) time in VC++5.0:
<blockquote>
<code>
using std::ostringstream;<br>
ostringstream os;<br>
for (int i = 0; i &lt; n; ++i)<br>
  os &lt;&lt; i;
</code>
</blockquote>
This severely impacts the performance
of conversion-to-string of breps and
meshes in Tcl/QMG.  It affects several other operations
as well.  To reduce the running time to O(n), make
the following change to include-file 
<code>SSTREAM</code>.
Replace the line
<blockquote>
<code>
   size_t _Ns = _Os + _Alsize;
</code>
</blockquote>
with
<blockquote>
<code>
   size_t _Ns = (_Alsize &gt; _Os)? _Os + _Alsize : 2 * _Os + 1;
</code>
</blockquote>

<p>
<strong>Note: changing standard headers will affect 
all your C++ development (not just QMG).  
Any changes you make to standard headers are 
ENTIRELY AT YOUR OWN RISK.  It is possible that the changes
proposed above will cause other software to malfunction.
The author of QMG, Cornell University
and other organizations involved with QMG offer NO WARRANTY
concerning patches to Visual C++ mentioned here
(or anything else mentioned in this documentation) and
disclaim all liability.
See the <a href="copyright.html">license terms</a> 
accompanying QMG for information about disclaimers.
</strong>


<h2> General hints on customization</h2>

You may have to spend some
effort in getting a working makefile. In general, it will be
easier to compile the software for Tcl/Tk than for for
Matlab. There are
two stumbling blocks in compiling QMG for Matlab.

<p>
The QMG source code uses a feature of the C++ language called
&#8220;templates.&#8221;
A template is a parameterized type and is associated with 
several parameterized functions.  These parameterized functions
must get instantiated by the C++ compiler into actual linkable
functions.  The instantiated template functions then must get stored
in a .o file somewhere that the C++ compiler knows about.  Different
C++ compilers handle this in different ways.  
For example, for the Mips-Pro 7.3 C++ compiler, the flag
<code>-ptused</code> is needed when compiling QMG for Matlab.

<p>
The second stumbling block in linking C++ object files to Matlab
concerns libraries.  A typical C++ compiler will link in one or more
different libraries whose names you may have to figure out.
Many Unix C++ compilers (not egcs though)
link a file called libC.a, so it is likely that you
will need -lC as an option to the link command.
<p>
Many C++ compilers have a option (possibly named -v)
to display the steps of compilation.
This will help you figure out which libraries are involved in linking
C++ code.  The mex command also has a -v option; this option will
should you what the default libraries used by mex are.  By experimenting
with these, you can probably figure out what additional -l and -L options to
give the link command.

<h2> Customizing the source code </h2>

It should not necessary to customize the source code itself for
various platforms because the C++ used is fully standard-conforming.  
There are some bugs in some of the compilers
which required special #ifdef/#endif
pairs in the source code.
The source code uses templates, the standard template library,
streams, inheritance, namespaces,
and exceptions. It also uses a very simple form of member templates.
Exceptions can be turned off (under Matlab)
by not defining ENABLE_EXCEPTIONS in the Makefile.  In this case,
when an error occurs and control is
returned back to Matlab,
QMG will not release memory allocated to it, and some files
may not be closed.  (Memory is released and files will be closed
when you exit Matlab.)

<p>
QMG 2.0 does not use RTTI, multiple inheritance, template 
specialization, default template arguments,
function templates.
On some platforms, you must enable RTTI even
though QMG does not use it because 
exception-handling may require RTTI.

<p>
QMG assume that unsigned ints have at least 32 bits.  If your system
uses fewer bits for unsigned ints, try modifying the <strong>typedef</strong>
 statement
for UInt32 in $QMG_ROOT/src/common/qnamesp.h.  Note: this has not been
tested.  Similarly, QMG assumes IEEE-conforming double-precision
arithmetic.  If your system uses some other kind of arithmetic, please
modify the constants BIG_REAL and MACHINE_EPS in that file.  Please
also change the global variable <code>gm_default_tol</code>
accordingly.

<h1><a name="env"> Setting up your environment</a> </h1>

For viewing 3D breps and surface meshes in Tcl QMG, 
you need a VRML viewer
installed in your web browser.  For information about VRML including
browsers,
see the 
<a href="http://www.web3d.org/vrml/">repository</a>.  You need
a viewer that can handle VRML 1.0.  Note: VRML 2.0 is not upward
compatible with VRML 1.0, but many VRML 2.0 viewers also support VRML 1.0.

<p>
You also need to set some environment variables.  These are
described in a readme file that is unpacked in the
$QMG_ROOT directory.  In particular, 
<ul>
<li>
if you download source code, see <code>readme_src</code>.
<li>
if you download Windows/Matlab executables, see <code>readme_matlab</code>.
<li>
if you download Windows/Tcl executables, see <code>readme_tcl</code>.
</ul>

 For example,
the environment variable QMG_ROOT should be set to the directory
where the software is installed.

<h1>Running QMG</h1>

Once the environment variables are set, you can run QMG.
To run the Matlab version of QMG, start matlab from the directory
$QMG_ROOT/ex.  This directory has a <code>startup.m</code> file that sets all
the paths correctly.  To run the Tcl/Tk version of QMG, change to
the <code>unixtcl</code> or <code>windowstcl</code> subdirectory
$QMG_ROOT/build.  In that directory there is an executable called
<code>qmg</code>.  Running this executable (no arguments) starts
QMG.

<h2>Testing</h2>
There are 11 tests shipped with QMG.
To run through all the tests at once,
execute the statement <blockquote><code>alltests</code></blockquote> in Matlab or
<blockquote><code>source $qmg_library2/alltests.tcl</code></blockquote> in Tcl/Tk.  This will
leave a series of files test1.di,...,test11.di 
that you can compare to the di files shipped with QMG
in directories $QMG_ROOT/tcl2 and $QMG_ROOT/mfiles2.
Running this command will take at least 5 minutes,
and possibly more than an hour, depending on the speed
of your computer.  The Matlab version takes slightly longer
because test7 solves a finite element problem in Matlab but
not in Tcl.

<p>
After <code>alltests</code> is done on either scripting language, there are two
global variables set, <code>meshsizesum</code>, which is the sum of
the number of vertices in each mesh generated by each test, and
<code>aspprod</code>, which is
the product of the worst-case aspect ratios of each mesh.  
These numbers should come out to 8473 and approximately 8.822e18.
If so, then you have successfully installed QMG.
<p>
The tests can also be run individually. In Matlab, this is
accomplished by typing <code>test1</code>, then <code>test2</code>, 
and so on.  In Matlab you can first issue an <strong>echo on</strong> or 
<strong>diary</strong> command.
To run the tests under
Tcl/Tk,  you can type either 
<blockquote>
<code>source $qmg_library2/test1.tcl</code>
</blockquote> or
<blockquote>
<code>gmevallog $qmg_library2/test1.tcl</code>
</blockquote>
 and so on up to <code>test11.</code>
The <code>source</code> command does not echo commands 
as they are executed, whereas
the <a href="ref.html#gmevallog"><code>gmevallog</code></a> command does.

<p>
If you are running the tests interactively, you can set the global
variable <code>interactive</code> to 1.  In Matlab this is done by:
<blockquote><code>
global interactive<br> 
interactive=1
</code></blockquote>
In Tcl/Tk this is done by: <code>set interactive 1</code> from
the QMG shell.  Setting this variable causes the tests to
generate plots and pause as they execute.
Finally, there is an interactive  script 
called testviz to test the graphics capabilities of
QMG.  
Type <code>testviz</code> in matlab or
<code>source $qmg_library2/testviz.tcl</code> in Tcl/Tk.

<hr>
<p>
This documentation is written by 
<a href="http://www.cs.cornell.edu/home/vavasis/vavasis.html">Stephen A. 
Vavasis</a> and is
copyright &#169;1999 by <a href="http://www.info.cornell.edu/CUHomePage.html">Cornell 
University</a>.
Permission to reproduce this documentation is granted provided this
notice remains attached.  There is no warranty of any kind on
this software or its documentation.  See the accompanying file
<a href="copyright.html">'copyright'</a>
for a full statement of the copyright.
<p>
<address>
Stephen A. Vavasis, Computer Science Department, Cornell University,
Ithaca, NY 14853, [e-mail]
</address>
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