Compiled MATLAB programs run slow.

[Eric27]

Hi all,

I've written a simple function to test the compiler:

function f = test()
tic
for i = 1:10000000
A = 2+5;
B = A/4;
end;
toc

The .m file run in about 0.1 seconds.
After I compile it(mcc -x test.m) the execution time increases to ~3 seconds.
I get the same effect if I compile it to a standalone.
-MATLAB version 6.5.1
-Compiler: Lcc C version 2.4 in C:\MATLAB6P5P1\sys\lcc

I did this after discovering that compiling a rather complex program I had written caused a slowdown.

Any ideas?

 

[pjordan]

I have the exact same problem using the mcc (a slowdown of approximately 4 times). I ended up rewriting the functions in C and then compiling them into MEX, which resulted in a 50 times speed-up. I'd really appreciate anyone's input on this. Thanks,

Petr

 

[red300zx99x]

I'm convinced MATLAB is just slow

 

[MikeyP]

I think you are being a little unfair with your test. The original function is badly written matlab code. If you were writing genuine matlab code to perform those 2 operations 10 million times you would write

function f = test()
tic
A = 2*ones(10000000,1) + 5*ones(10000000,1);
B = A./4;
toc

Matlab is not designed to work quickly with for loops.

M


--
Dr Michael F Platten