Thread Subject: Calling binary reading m-script from .c exe file (mex)

Hi!


Background:
-----------
I have a binary data file created by MODFLOW (a groundwater
modelling software), which I need to extract data from. I
do not know the exact structure of the file, but MATLAB's
fread function reads it anyways.

The problem is that I need to read the data over and over
again, invoking the process each time from the Windows
command prompt, as part of a calibration routine running
under the Windows prompt.

In order to only have one MATLAB engine running, my idéa is
to do this through an executable file made in C (or C++),
compiled using the mex function.

A have based my script on the example file "engwindemo.c"
from MATLAB's Help, so I know that the basics work (engine
start up, passing simple commands like "A = 2 + 4;", etc.).


Problem/Question:
-----------------
I have not been able to make fread work as part of my
c-file. Basically, nothing happens. Does mex not support
a call to certain MATLAB functions, like fread? Is there a
list of supported functions somewhere (I have looked).

Ideally, I would like to have a simple c-code program, which
just passes a call to a MATLAB script that executes as if it
was called from the MATLAB prompt. E.g.:

    engEvalString(ep, "plotter.m");

should equal

    >> plotter

I have attacked my "reading the binary data"-problem in many
different ways, but I am running out of idéas now, so I
really hope one of you guys can help me!

Cheers, Lars

"Lars Christiansen" <lac@er.dtu.dk> wrote in message
<ff7obh$ku8$1@fred.mathworks.com>...
> Hi!
>

Hi again!

Problem solved (with a little help from a friend).

I needed to (1) set _absolute_ paths in my m-scripts and (2)
include the m-script I call from the c-code executable file
in the MATLAB paths. Reason: when the MATLAB engine starts
up, it does _not_ start up in the present working directory.

In this way, I now have a simple exe-file which calls a
m-script that takes care of all the rest for me.

Have a nice weekend!
Lars

On Fri, 19 Oct 2007 10:16:46 +0000 (UTC), "Lars Christiansen"
<lac@er.dtu.dk> wrote:

>"Lars Christiansen" <lac@er.dtu.dk> wrote in message
><ff7obh$ku8$1@fred.mathworks.com>...
>> Hi!
>>
>
>Hi again!
>
>Problem solved (with a little help from a friend).
>
>I needed to (1) set _absolute_ paths in my m-scripts and (2)
>include the m-script I call from the c-code executable file
>in the MATLAB paths. Reason: when the MATLAB engine starts
>up, it does _not_ start up in the present working directory.
>
>In this way, I now have a simple exe-file which calls a
>m-script that takes care of all the rest for me.
>
>Have a nice weekend!
>Lars

Another solution, which I employ in all of my engine applications, is
to set the working directory of the MATLAB engine automatically right
after it is opened from within the c-code. I use getcwd(cwd) in the
c-code, construct another string with "cd '"+cwd+"';", and then call
engEvalString with this command. That gets the engine pointed to the
c-code directory regardless of where the c-code is running from. I
also use chdir(cwd) and another engEvalString call to change working
directories and still force the engine to point to the c-code working
directory.

James Tursa

Hi Lars and everybody ,
Do you have a program on matalb or any on language to read the MODFLOW output files (cell by cell file, as binary type)? I can read the cell by cell budget binary file in ZoneBudget, MODPATH, GW Chart and ModelMuse. But I need to read and imported in matlab to do some calculation in matlab.
Thank you in advance!
best regards,
Mustafa


"Lars Christiansen" <lac@er.dtu.dk> wrote in message <ffa06e$537$1@fred.mathworks.com>...
> "Lars Christiansen" <lac@er.dtu.dk> wrote in message
> <ff7obh$ku8$1@fred.mathworks.com>...
> > Hi!
> >
>
> Hi again!
>
> Problem solved (with a little help from a friend).
>
> I needed to (1) set _absolute_ paths in my m-scripts and (2)
> include the m-script I call from the c-code executable file
> in the MATLAB paths. Reason: when the MATLAB engine starts
> up, it does _not_ start up in the present working directory.
>
> In this way, I now have a simple exe-file which calls a
> m-script that takes care of all the rest for me.
>
> Have a nice weekend!
> Lars

> Another solution, which I employ in all of my engine applications, is
> to set the working directory of the MATLAB engine automatically right
> after it is opened from within the c-code. I use getcwd(cwd) in the
> c-code, construct another string with "cd '"+cwd+"';", and then call
> engEvalString with this command. That gets the engine pointed to the
> c-code directory regardless of where the c-code is running from. I
> also use chdir(cwd) and another engEvalString call to change working
> directories and still force the engine to point to the c-code working
> directory.

So I tried this procedure but with no luck. I still get the error message
"??? Undefined function or variable 'myFunc'." The engine can't find my custom function in a m-file existing in the set working directory.

I'm using Mac OS and Matlab 2008. Are there any buggs known? Can this be reported to work?