Running Matlab through PHP not quite working.

So I have this line in my PHP code:

exec('start /b matlab -nosplash -nodesktop -minimize -r Matlab3("C:\xampp\htdocs\temp\test_file.txt")');

And I can see Matlab start, and stay running in my Windows Task Manager, but it doesn't actually do any of the things its supposed to do (save a text file it creates, save a picture it takes).

HOWEVER, if I go to my command prompt, and type start /b matlab -nosplash -nodesktop -minimize -r Matlab3("C:\xampp\htdocs\temp\test_file.txt")

Then it works perfectly. What can I do to make it work via PHP?

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Any help?