Format distance matrix

`Z = squareform(y)`

y = squareform(Z)

Z = squareform(y,'tovector')

Y = squareform(Z,'tomatrix')

`Z = squareform(y)`

, where `y`

is
a vector as created by the `pdist`

function,
converts `y`

into a square, symmetric format `Z`

,
in which `Z(i,j)`

denotes the distance between the `i`

th
and `j`

th objects in the original data.

`y = squareform(Z)`

, where `Z`

is
a square, symmetric matrix with zeros along the diagonal, creates
a vector `y`

containing the `Z`

elements
below the diagonal. `y`

has the same format as the
output from the `pdist`

function.

`Z = squareform(y,'tovector')`

forces `squareform`

to
treat `y`

as a vector.

`Y = squareform(Z,'tomatrix')`

forces `squareform`

to
treat `Z`

as a matrix.

The last two formats are useful if the input has a single element, so that it is ambiguous whether the input is a vector or square matrix.

y = 1:6 y = 1 2 3 4 5 6 X = [0 1 2 3; 1 0 4 5; 2 4 0 6; 3 5 6 0] X = 0 1 2 3 1 0 4 5 2 4 0 6 3 5 6 0

Then `squareform(y) = X`

and ```
squareform(X)
= y
```

.

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