When you have questions like this, LOOK AT THE HELP. READ IT! At the command line in MATLAB, try this:
help triplequad
doc triplequad
If you want more information, then
type triplequad
In either case, you will learn that quad is the tool used by default, but that if you prefer, you can also tell it to use other routines like quadl. You can use any quadrature scheme in fact, with only the requirement that it has the same calling sequence as those tools.
% Q = TRIPLEQUAD(FUN,XMIN,XMAX,YMIN,YMAX,ZMIN,ZMAX,TOL,@QUADL) uses
% quadrature function QUADL instead of the default QUAD.
Therefore quad is the default. quad is an implementation of an adaptive Simpson quadrature.
