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The following functions allow you to determine the size of a variable or
expression. These functions are defined for all objects. They return
-1 when the operation doesn't make sense. For example, Octave's
data structure type doesn't have rows or columns, so the `rows`

and
`columns`

functions return -1 for structure arguments.

__Built-in Function:__**ndims***(*`a`)Returns the number of dimensions of array

`a`. For any array, the result will always be larger than or equal to 2. Trailing singleton dimensions are not counted.

__Built-in Function:__**columns***(*`a`)Return the number of columns of

`a`.

**See also:**size, numel, rows, length, isscalar, isvector, and ismatrix.

__Built-in Function:__**rows***(*`a`)Return the number of rows of

`a`.

**See also:**size, numel, columns, length, isscalar, isvector, ismatrix.

__Built-in Function:__**numel***(*`a`)Returns the number of elements in the object

`a`.

**See also:**size.

__Built-in Function:__**length***(*`a`)Return the `length' of the object

`a`. For matrix objects, the length is the number of rows or columns, whichever is greater (this odd definition is used for compatibility with MATLAB).

__Built-in Function:__**size***(*`a`,`n`)Return the number rows and columns of

`a`.With one input argument and one output argument, the result is returned in a row vector. If there are multiple output arguments, the number of rows is assigned to the first, and the number of columns to the second, etc. For example,

size ([1, 2; 3, 4; 5, 6]) ⇒ [ 3, 2 ] [nr, nc] = size ([1, 2; 3, 4; 5, 6]) ⇒ nr = 3 ⇒ nc = 2

If given a second argument,

`size`

will return the size of the corresponding dimension. For examplesize ([1, 2; 3, 4; 5, 6], 2) ⇒ 2

returns the number of columns in the given matrix.

**See also:**numel.

__Built-in Function:__**isempty***(*`a`)Return 1 if

`a`is an empty matrix (either the number of rows, or the number of columns, or both are zero). Otherwise, return 0.

__Built-in Function:__**sizeof***(*`val`)Return the size of

`val`in bytes

__Built-in Function:__**size_equal***(*`a`,`b`, …)Return true if the dimensions of all arguments agree. Trailing singleton dimensions are ignored.

**See also:**size, numel.

__Built-in Function:__**squeeze***(*`x`)Remove singleton dimensions from

`x`and return the result. Note that for compatibility with MATLAB, all objects have a minimum of two dimensions and row vectors are left unchanged.

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