Format distance matrix

converts `ZOut`

= squareform(`yIn`

)`yIn`

, a pairwise distance vector of length
*m*(*m*–1)/2 for *m*
observations, into `ZOut`

, an
*m*-by-*m* symmetric matrix with zeros
along the diagonal.

The pairwise distances in `yIn`

are arranged in the order
(2,1), (3,1), ..., (*m*,1), (3,2), ...,
(*m*,2), ..., (*m*,*m*–1).
The pairwise distance between the `i`

th and
`j`

th observations is in `ZOut(i,j)`

and
`yIn((i–1)*(m–i/2)+j–i)`

for *i*≤*j*.

forces `yOut`

= squareform(`ZIn`

,'tovector')`squareform`

to treat `ZIn`

as a
matrix and converts `ZIn`

into a vector. If
`ZIn`

is a scalar (1-by-1), then `ZIn`

must be zero.

The previous two syntaxes are useful when the input argument is a scalar. If
you do not specify either `'tomatrix'`

or
`'tovector'`

, then the default is
`'tomatrix'`

.

You can use

`squareform`

to format a vector or matrix that is similar to a distance vector or matrix, such as the correlation coefficient matrix (`corrcoef`

).