length

Arguments

M

a matrix (usual or polynomial or character string) or a list.

n

an 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.

Examples

length([123 ; 456 ])
length(['hello world',SCI])
length(rand(2,2,2))

a = mlist(["myMlistT" "field1" "field2"],"aexample","bexampleb");
length(a)
// returns 3 default behaviour if length not overloaded for mlist

// we create an overload function for mlist of type myMlistT
function r=%myMlistT_length(M)
    r = length(M.field1)
endfunction

length(a)
// returns 8 result of length(a.field1)

See also

• size — size of objects

History