MINMAX find kth smallest or largest values and their indices.

USAGE:
vals = minmax(data) % find minimum
vals = minmax(data,k) % find kth smallest values
vals = minmax(data,k,flag) % find kth largest values
[vals,loci] = minmax(:)
[vals,loci,locj] = minmax(:) for 2 d array
[vals,loci,locj,...] = minmax(:) % for multi dimensional array

INPUT:
data - two dimensional data
k - number of smallest or largest values required
flag - whether min or max

OUTPUT:
vals - smallest or largest values
loci - index to the row
locj - index to the column

EXAMPLES:
data = 1:16;
data = reshape(data,4,4);
[out,loci,locj] = minmax(data,5) % find the 5 smallest vaues and
their locations
[out,loci,locj] = minmax(data,5,'max) % find the 5 largest vaues and
their locations