lengthNumber of characters of a string. Number of elements of an array or list.Syntaxn = length(M)ArgumentsM
a matrix (usual or polynomial or character string) or a
list.
nan integer or a matrix of integers.Description
For usual or polynomial matrix n is the integer
equal to number of rows times number of columns
of M. (Also valid for M
a boolean matrix).
For matrices made of character strings (and in particular for a
character string) length returns in
n the length of entries of the matrix of
character strings M.
The length of a list is the number of elements in the list (also
given by size).
The length of an array M of cells or of structures is the number of elements of the array.
It is equivalent to size(M, "*").
The length of a mlist is by default the number of elements in the
mlist, but you can overload it (see example). Note that for a non-string
hypermatrix, there is no need to overload the function. Indeed, length
returns the product of the dimensions of the hypermatrix.
length('123') is 3.
length([1,2;3,4]) is 4.
WARNING : length of a sparse matrix
returns the max of dimensions and not the product
of the dimensions. (For example:
length(sparse(eye(12,2)))
returns max(12,2) and not 24).
Please use size(...,'*') with sparse matrix.
ExamplesSee also
size
History5.4.0
This function allows overloading for mlist type.
6.0.0
The length() of any array C of cells was formerly
always 3, whatever are the number of dimensions and the sizes of the
array. It is now the number of elements of the array at null depth
(without recursive counting), equal to size(C, "*").
The length() of any array S of structures was formerly
equal to its number of fields +2, whatever are the number of dimensions
and the sizes of the array. It is now the number of elements of the
array at null depth, equal to size(S, "*").