# Documentation

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# squareform

Format distance matrix

## Syntax

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

## Description

`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.

## Examples

```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```.

## See Also

#### Introduced before R2006a

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