MATLAB: Do I receive an error when I execute an M-file in the Linux shell using the -r flag in MATLAB 7.11 (R2010b)

batchcommandconsoledosMATLABpromptscriptshell

I have a function which executes without errors in MATLAB. However, when I try to execute it in the Linux shell using the following code (which contains the -r flag), I receive an error and have to type "exit" to quit the program.

matlab -r myfile.m

Best Answer

Remove remove the ".m" extension from the function name after the -r flag.

Explanation: When using matlab with the “-r” flag, the subsequent argument is interpreted as a MATLAB command, not as an input filename. It is the same as if you were directly typing the commands after “-r” into the MATLAB command prompt. For example, if you wish to execute a file called “myfile.m”, the MATLAB command “myfile” runs the file. With the “.m” extension, it treats the function as if it returns a structure and then attempts to access the “m” field of that structure. A warning first occurs because the programming practice is deprecated, then an error occurs because the function actually does not return a structure object.

Related Solutions

MATLAB: Does the MATLAB file script/function execute slower when passed to MATLAB using the standard input as opposed to when it is called from the MATLAB command prompt

This is the expected behavior. Passing a file to MATLAB through the standard input executes each line of the file at the command line and does not take advantage of the JIT.

To work around this issue, use the '-r' flag when calling MATLAB to pass a file to MATLAB which will cause the file to be executed as a script/function. For example,

matlab -r filename

MATLAB: M-file function

Your function is calling itself without approaching any convergance or something that will allow it to end. Therefore it will run forever and eventually out of memory (hence the error). Try splitting it up into a script and a function as so:

Script:

 %creating window of plot from -5 to 50 using stepsize 0.25 for t x-axis
 %t should be on the x axis, v should be on the y axis
 k=0; 
for i= -5:.25:50
    k = k+1;
    t(k)=i;
    v(k)=vPieceWise(t(k));
end 
plot(t,v);
 
figure
plot(t,v);
hold on

Function:

%Part A: Mfile function to compute v as a function of t
function v = vPieceWise(t)
 if (t < 0)
        v = 0;
    elseif (0 <= t)&&(8<=16)
        v = -5*t+10*t.^2;
    elseif (8<=16)&&(t<=16)
        v = 624 - 3*t;
    elseif (t<=16)&&(t<=26)
        v = 12*(t-16).^2+36*t;
    elseif (26<t)
        v = 2136*exp(-0.1*(t-26));
 end

Best Answer

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MATLAB: Does the MATLAB file script/function execute slower when passed to MATLAB using the standard input as opposed to when it is called from the MATLAB command prompt

MATLAB: M-file function

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