Do you mean the MAT-file format? Yes that's possible. However there are several versions/formats around.

Copied from the docs:

Level 5 MAT-files are made up of a 128-byte header followed by one or more data elements. Each data element is composed of an 8-byte tag followed by the data in the element. The tag specifies the number of bytes in the data element and how these bytes should be interpreted; that is, should the bytes be read as 16-bit values, 32-bit values, floating-point values or some other data type.

You will have to construct the files yourself using pack as suggested above.

See matfile_format.pdf for a good description of the different formats.

Cheers,

Harry

I'm so happy I don't have to work with MATLAB, IDL and other $%^$^$[!#~) languages anymore:)