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Why is c++ taking longer than MATLAB?

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Old   April 25, 2017, 03:36
Unhappy Why is c++ taking longer than MATLAB?
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Rob
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Comparing my run times with other people coding the same method is revealing that my c++ code is taking about 30% longer than their MATLAB codes when it should be much, much faster. I cannot seem to figure out why is this.

I use Visual studio 2015 community as my compiler.

I use of Ox (full optimization).

My hardware is comparable to my peers.

Anyone have any ideas?
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Old   April 25, 2017, 04:00
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Anton Kidess
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You wrote poorly optimized code.
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Old   April 25, 2017, 14:14
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Well from what i know, is that i compared once codes : Python & Matlab & Fortran , the Fortran is the most faster.

To answer your question :

you can install ( openmpi ) than try some tutorials to make your code parallel and if your machine has 4 processors your code will be 4Xtimes faster
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Old   April 25, 2017, 14:23
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If he managed to get slower execution in c++ than in matlab I don't think parallelization is the next logical step.
He should really investigate what slows down his code, for example by using a profiling tool.
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Old   April 25, 2017, 20:47
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For many built-in functions, Matlab accelerates the routine by running them in parallel. I.e. max, min, etc. Is your c++ purely serial? Are you even comparing the same code?
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Old   April 30, 2017, 12:05
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Since you are using Visual Studio, if you forgive me for being so obvious, are you sure you are "running" the code? Perhaps you are debugging the code using built in F5 (at least this was the way it was in an older Visual Express) so the IDE is actually losing time debugging your time. You might want to try reaching the directory where your .exe file is and run it from there perhaps?
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Old   April 30, 2017, 13:34
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I don't know how your code is or what it does. Are they using sparse matrices in Matlab? They reduce the calculation allot.
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