
 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.


 Example

Suppose we have a simple 3 x 4 matrix A containing some
random integer elements

  --> A = randi(ones(3,4),10*ones(3,4))

  A =
    2  3  2  3
   10  2  4  8
    5 10  1  2

We can extract the elements (1,3),(2,3),(3,4) of A via
sub2ind. To calculate which elements of A this corresponds
to, we can use sub2ind as

  --> n = sub2ind(size(A),1:3,2:4)

  n =
    4  8 12

  --> A(n)

  ans =
   3 4 2


* FreeMat_Documentation
* Elementary_Functions
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