Comments on: Existence in MATLAB

By: Loren

Loren — Tue, 22 Jan 2008 21:09:03 +0000

Saadia and Peter-

The problem is, you have a created a variable called myFile so asking if it exists gets things in a mess. And there probably isn’t a file itself named ‘myFile’ but the contents of myFile. You need to do this:

if exist(myFile,’file)
…

which will use the contents of the variable myFile

or you might be able to use which, but in functional form

which(myFile)

and see if it returns empty or not (though I don’t think which will work for something not on the matlabpath).

–Loren

By: Saadia Iftikhar

Saadia Iftikhar — Tue, 22 Jan 2008 17:29:54 +0000

How to deal with problem which Peter addressed? If File is in MAT format and want to check its existence? How to do this?

peter replied on October 4th, 2006 at 7:49 pm :

Yes, but what about

myFile = [path filesep ‘foo.mat’];
if ~exist(’myFile’, ‘file’)
%create the file
end

By: peter

peter — Thu, 05 Oct 2006 00:49:44 +0000

Yes, but what about

myFile = [path filesep ‘foo.mat’];
if ~exist(’myFile’, ‘file’)
%create the file
end

This fails, because Matlab returns 0, thinking that myFile is a var (which it is, but it’s also a file). Hardcoding the string, of course, works.

By: loren

loren — Mon, 06 Feb 2006 12:31:38 +0000

You can in MATLAB or the Instrument Control Toolbox. A good place to look for this sort of information is The MathWorks support page. You can search for the function serial and read the documentation beyond the reference pages. There are also some illustrative demo pages.

By: david

david — Sun, 05 Feb 2006 02:09:01 +0000

Hello.

Great blog. It is really helpfull with some aspects of Matlab.
I would like to ask you if it is possible to control a device with matlab or “data acquisition toolbox” trough the serial port RS-232.

thank you.