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.
| columns (a) | Function File |
| Return the number of columns of a. |
| rows (a) | Function File |
| Return the number of rows of a. |
| length (a) | Built-in Function |
| 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). |
| size (a n) | Built-in Function |
|
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 ([1 2; 3, 4; 5, 6], 2)
=> 2
returns the number of columns in the given matrix. |
| isempty (a) | Built-in Function |
| 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. |