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Some miscellaneous topics:
Command line options
The syntax for starting the Evolver from the system command prompt is:
evolver [-ffilename] [-a-] [-d] [-e] [-i] [-m] [-pn] [-q] [-Q] [-w] [-x] [-y] [datafile]
The current directory and EVOLVERPATH
will be searched for datafile. If the datafile is not found, then a new
search with extension
.fe is done.
Wildcard matching is in effect
on some systems (Windows, linux, maybe others), but be very careful when
using wildcards since there can be unexpected matches.
If the datafile is still not found, or the
datafile is not given on the command line, then the user will be prompted.
Do not enable automatic conversion to
named methods and
quantities mode when a
situation requiring it arises (for debugging).
- Prints YACC debugging trace as datafile is parsed. May be helpful if
you can't figure out why your datafile doesn't get read in properly AND
you know YACC.
Echo input. Meant for echoing commands of piped input to
screen so the user can follow what is going on in case Evolver is being
controlled by another process.
- Specifies the name of a file to be used as command input after the
datafile is read. At the end of this file, input reverts to standard input.
The effect is the same as redirecting input from the file, except that
-f will echo commands to the screen and revert to standard input at the
end. Also note that errors will cause input to revert to standard input.
- Keeps elements numbers as listed in the datafile, instead
of renumbering them consecutively. The same effect can be achieved
by putting the keyword
in the top of the datafile.
- Turn memory debugging on at start of program. Same effect as Evolver
memdebug toggle command.
- Forces use of n processes for an Evolver compiled in multi-processor
mode. n may be larger or smaller than the physically available number of
processors. The default is 1. This option should be regarded as experimental;
there is still too much overhead for it to be useful usually.
- Convert everything to named quantities internally.
There are a few things for which no quantities exist yet; they will produce
- Suppresses echoing of
read section of datafile, and of
files input with the read command;
- Causes Evolver to exit whenever a warning occurs. Meant to be used when
Evolver is run in a shell script.
- Causes Evolver to exit whenever an error occurs. Meant to be used when
Evolver is run in a shell script, so that Evolver doesn't get hung up waiting
for input in response to an error.
- Causes Evolver to cease execution of commands and return to command
prompt after any warning message. Same effect as
Bug reports should be submitted by email to
Please include the Evolver version number, a description of the problem,
the initial data file, and the sequence of commands necessary to reproduce
The group of Surface Evolver users has grown large enough that I have
started a newsletter. Contents include announcement of new versions and
latest features, bibliography, and anything else anybody would like to
contribute. If you would like to be on the mailing list, send your email
When the Surface Evolver detects an error, it prints an error message
and tries to take appropriate action. If the -x
command line option was given when Evolver was started, then Evolver exits
immediately with a nonzero error code. This is useful when running Evolver
from shell scripts. There are several categories of
WARNING - Something has happened that you should know about,
but Evolver proceeds normally after printing the message. By setting
break_after_warning toggle, you can make Evolver then
cease execution at the end of the current command or subcommand.
By setting the
break_on_warning toggle, you can make
Evolver return immediately to the command prompt. The
-y command-line option makes the Evolver exit after
a warning, useful in batch runs.
SYNTAX ERROR - The parser has detected an error. Recent input
up to the detection of the error is printed, but the actual problem may
DATAFILE ERROR - There is an error in the datafile being read
in. Evolver attempts to recover by skipping to the next recognizable part
of the datafile, but will abandon the datafile after 5 such errors.
The surface data that was read in is available for your inspection,
but it probably forms an inconsistent surface and you should not try
to evolve it.
ERROR - This is an error encountered during the execution
of a command. The command is abandoned and Evolver returns to the main
prompt. The actions of the command are not undone.
-x command line option makes Evolver exit immediately
after any error; useful batch runs.
FATAL ERROR - An error from which recovery is impossible.
Evolver exits immediately.
Whenever the Surface Evolver loads a new surface, either on startup
or in response to the q
commands, the following actions occur:
- Any previous surface has all memory deallocated. All user-defined variables
and commands are deleted, including any currently executing commands.
- Internal variables are initialized to default values.
- The datafile is read in.
- In the soapfilm model, any nontriangular
face is divided into triangles by creating a vertex in the center and making
edges from the center to the vertices.
- In the soapfilm model, the order
of facets around each edge is determined geometrically.
- Vertices are projected to any level set constraints.
- Checks as described for the C command are
- Initial areas, energies, and volumes are calculated.
- The viewing matrix is reset
to center the object in the graphics window.
- If any graphics are active, the new surface is drawn.
- The main command prompt is started.
Evolver operation may be interrupted with the standard keyboard interrupt,
CTRL-C usually (SIGINT for you unix gurus). During repeated operations,
this will set a flag which is checked at the end of each loop. Repetition
will cease after the current step and control will return to the main prompt.
If you give a second interrupt before the loop has ended, Evolver will
abort the command and return to the main prompt. Beware that this may leave
the surface in an inconsistent state if surface topology changing operations
were going on. An immediate abort will also happen if an interrupt is received
outside a loop. If Evolver receives SIGTERM (say from the unix kill command),
it will dump to the default
dump file and exit. This is useful for stopping
a background Evolver running a script. The same thing will happen with
SIGHUP, so losing a modem connection will save the current surface.
Note: In Microsoft Windows, the second interrupt doesn't do anything much
since Windows creates a separate thread to handle the interrupt, and
I can't find any way to force the offending thread to stop and longjmp
back to where it should. So if the Evolver is really, really stuck,
you may just have to kill the whole program.
Parallel versions of the Surface Evolver are available for several
types of systems, but these are experimental and not very useful.
For symmetric multiprocessors (several CPUs in the same machine), the
-pn command line option will cause Evolver to use
n threads, so it is best if n does not exceed the
number of CPUs in the machine.
It will slow things down to use more threads than are physically
available, but it is possible to run multiple threads on a single-processor
system for testing.
Currently, the only calculations done in parallel are the
named quantities, so it is best to start Evolver with the -q
Evolver seems to be memory bandwidth limited, so
you may not get as much speed-up as you wish.
For distributed computation, there is an MPI
version of Evolver, but this is still experimental and not useful
except in very special circumstances.
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