MATLAB: Different behaviour while running Matlab script from DOS window

dos command prompt

Hi,

I have a problem starting Matlab from DOS window for different versions of Matlab.

When I call Matlab 2010bSp1 (32 bit) from DOS window to run a script, I do not see any problem.

C:\ProgramFiles\matlab\r2010bsp1\bin\matlab.exe -r "add.m"

When I call Matlab 2014a (64 bit) from DOS window to run the same script, I see a problem

C:\ProgramFiles\matlab\r2014a\bin\matlab.exe -r "add.m"

The MATLAB command window shows Undefined variable "add" or function "add.m".

Note that the path of "add.m" is not added to search path of Matlab in either case.

Can anyone please let me know why MATLAB r2014a version is not able to identify "add.m"?

Any help is highly appreciated.

Best Answer

In the R2010b timeframe, the command

add.m

would generate the error message

??? Undefined function or variable 'add'.

In R2014a the same basic message is

Undefined variable "add" or function "add.m".

By R2016a the message had become

Undefined variable "add" or class "add.m".

The difference between R2010b and R2014a reflects an underlying change in processing. In R2010b, if the function add did exist in scope, then when the syntax add.m was used, add would be invoked with no arguments, and if that did not lead to an error message itself, MATLAB would then fail trying to access the field m of the function return value (even if a structure with that field was returned) because it is not permitted in MATLAB to subsref the result of a function call. But by the time of R2014a, MATLAB's parser had been extended to examine the call as a whole and reject it as being invalid without having invoked the function add in that situation.

This does lead to a difference: in the R2010b timeframe, if the function add existed and contained a quit() or exit() call that was executed, then MATLAB would exit before it noticed that taking a structure reference off of a function return value was invalid. But in later versions, because the function would not be invoked at all in that situation, you would end up with the error message.

So, long story short: do not include the '.m' in a function call. You can include it in a run action, but not in a function call.

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MATLAB: Which file Matlab selects if two different files with the same name are put under two folders, which are both added via addpath

This is a known issue with addpath function in MATLAB R2017a and R2017b. This got fixed in R2018a. It is recommended to update the MATLAB version.

As a workaround for this issue is to remove the path and then add. This results in adding the path at top.

addpath(genpath('subfolder1'))
addpath(genpath('subfolder2'))
% Perform the required operations
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rmpath('subfolder1')
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MATLAB: How to call MATLAB from the DOS prompt

To start MATLAB from a DOS window running inside Windows, do the following:

1. Open a DOS prompt

2. Change directories to $MATLABROOT\bin

(where $MATLABROOT is the MATLAB root directory on your machine, as returned by typing

matlabroot

at the MATLAB Command Prompt.)

3. Type "matlab"

You can also create your own batch file in the $MATLABROOT\bin directory

NOTE: If you have other commands that follow the call to MATLAB in your batch file, use matlab.exe rather than matlab.bat. If you call on matlab.bat, subsequent commands in the batch file will not get executed.

To do so, use the following instructions:

1. Create a file called mat.bat and place the following line into it:

 win $MATLABROOT\bin\matlab.exe

2. Insert $MATLABROOT\bin into the path in the autoexec.bat file.

(where $MATLABROOT is the MATLAB root directory on your machine, as returned by typing

matlabroot

at the MATLAB Command Prompt.)

Now you can type "mat" at the dos prompt and Windows will come up with MATLAB.

You can run MATLAB from the DOS prompt and save the session to an output file by doing the following:

 matlab -r matlab_filename_here -logfile c:\temp\logfile

Depending on the directory you are in, you may need to specify the path to the executable. The MATLAB file you want to run must be on your path or in the directory. This MATLAB file can be a function that takes arguments or a script.

When running a script 'myfile.m', use the following command:

 matlab -r myfile

When calling a function 'myfile.m' which accepts two arguments:

 matlab -r myfile(arg1,arg2)

To pass numeric values into 'myfile.m' simply replace 'arg1' and 'arg2' with numeric values. To pass string or character values into 'myfile.m' replace 'arg1' and 'arg2' with the string or character values surrounded in single quotes. For exampl to pass the string values 'hello' and 'world' into 'myfile.m' use the following command:

 matlab -r myfile('hello','world')

Note that the logfile will contain everything that was displayed to the Command Window while the MATLAB file was running. If you want to generate any print files you need to do this in the MATLAB file. You can combine this example with the above one to create a batch file that takes input files and creates output files.

In addition, this will call up an additional instance of the MATLAB command window. If you wish this to exit after the computation is complete, you will need to add the command 'exit' to the end of your MATLAB file. You can suppress the splash screen by adding the -nosplash flag to the above command so it looks like the following:

 matlab -nosplash -r mfile -logfile c:\temp\logfile

Although you cannot prevent MATLAB from creating a window when starting on Windows systems, you can force the window to be hidden, by using the start command with the -nodesktop and -minimize options together:

 start matlab -nosplash -nodesktop -minimize -r matlab_filename_here -logfile c:\temp\logfile

If you would like to call multiple MATLAB functions using the -r switch you could write a single function which will call each of the other MATLAB functions in the desired order.

Note: Batch files can be called from Windows scheduler in order to run MATLAB commands at specific times. May not work for UNC pathnames.

Best Answer

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