MATLAB Compiler

Nonscalar Arrays

(fold_non_scalar_mxarrays) This optimization is very similar to fold_scalar_mxarrays. It folds nonscalar mxArray values into compile-time arrays that are initialized at program start-up. This can have a large performance impact if you are constructing arrays that use [] or {} within a loop. This optimization makes the code less readable. For example,

function y = test
y = [ 1 0; 0 1] * [ pi pi/2; -pi -pi/2 ];

If you compile this with the -O none option, you get

...
mlfAssign(
  &y,
  mclMtimes(
    mlfDoubleMatrix(2, 2, _array0_, (double *)NULL),
    mlfDoubleMatrix(2, 2, _array1_, (double *)NULL)));
...

Compiling with -O none -O fold_non_scalar_mxarrays:on gives

...
mlfAssign(&y, _mxarray0_);
...

Optimizing Arrays

Optimizing Loops