Converts a vector-form distance vector to a square-form distance
matrix, and vice-versa.
X : ndarray
Either a condensed or redundant distance matrix.
Y : ndarray
If a condensed distance matrix is passed, a redundant
one is returned, or if a redundant one is passed, a
condensed distance matrix is returned.
As with MATLAB(TM), if force is equal to ‘tovector’ or
‘tomatrix’, the input will be treated as a distance matrix
or distance vector respectively.
If checks is set to False, no checks will be made
for matrix symmetry nor zero diagonals. This is useful if
it is known that X-X.T1 is small and diag(X) is
close to zero. These values are ignored any way so they do
not disrupt the squareform transformation.