Checks or fixes the given distance matrix specification and returns an
equivalent, symmetric `matrix`

object with 0s in the diagonal.

check.dist(x)

## Arguments

x |
an object (or list of objects) specifying a distance matrix |

## Value

a symmetric `matrix`

object (or list of such objects) of the
same dimension as `x`

## Details

If the argument is a matrix, check whether it is a valid specification of a
distance matrix and return it, making it symmetric if it isn't already.

If the argument is a list, calls `check.dist`

on every of its elements
and returns a list of the results.

For all other object types, attempts to coerce the argument to a `dist`

object and return the corresponding distance matrix (see above).

## See also