|GNU Octave Manual Version 3|
by John W. Eaton, David Bateman, Søren Hauberg
Paperback (6"x9"), 568 pages
RRP £24.95 ($39.95)
3.2 Object Sizes
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
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,
sizewill return the size of the corresponding dimension. For example
size ([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.
|ISBN 095461206X||GNU Octave Manual Version 3||See the print edition|