Specifying optimization flags in mex

I know that -O is implemented by default when I use the mex command

mex file.cpp

However, I have two questions related to that

(1) Is -O the same as -O when compile c++ files with g++ (i.e. when I'm not using mex)

(2) How can I implement -O3 without a makefile?

Answer 1

[Walter Roberson]

"(1) Is -O the same as -O when compile c++ files with g++ (i.e. when I'm not using mex)"

Yes. However, -O for mex is treated as -O2 instead of bare -O

"(2) How can I implement -O3 without a makefile?"

Use

   mex -v YourFileName.c

and look through the output for COPTIMFLAGS . Copy the flags there changing -O2 to -O3 and insert that into

mex COPTIMFLAGS="THOSE GO HERE" YourFileName.c

for example,

mex -v COPTIMFLAGS="-O3 -fwrapv -DNDEBUG"  tt.c

[Royi Avital]

Isn't there a dedicated command for Macros?

[Walter Roberson]

There is a series of functions for adjusting various aspects of the toolchain, and it is plausible that you might be able to use the functions to request a copy of the current toolchain, and modify that, and save it, after which there would be a command to activate it. Or perhaps that only applies to MATLAB Compiler or Coder; I am not sure.

There is no simple command along the lines of

mexconfig optimize -O3  %does not exist