SUB2IND SUB2IND Convert Multiple Indexing To Linear Indexing

Usage

The sub2ind function converts a multi-dimensional indexing expression
into a linear (or vector) indexing expression.  The syntax for its use
is

   y = sub2ind(sizevec,d1,d2,...,dn)

where sizevec is the size of the array being indexed into, and each
di is a vector of the same length, containing index values.  The basic
idea behind sub2ind is that it makes

  [z(d1(1),d2(1),...,dn(1)),...,z(d1(n),d2(n),...,dn(n))]

equivalent to

  z(sub2ind(size(z),d1,d2,...,dn))

where the later form is using vector indexing, and the former one is using
native, multi-dimensional indexing.
