Powerpoint save as or export to PDF

I am creating a Powerpoint using MATLAB and actxserver. I can save the file easily enough but it's too large. I need to compress it.

Could someone tell me how to save as or export as a PDF?

ppt = actxserver('PowerPoint.Application'); op = invoke(ppt.Presentations,'Open',strFileName,[],[],0); ... invoke(op,'SaveAs',strFileNameOut,1); invoke(op,'Close'); invoke(ppt,'Quit');

TIA,

Michael