length length of object n = length(M) M a matrix (usual or polynomial or character string) or a list. n an integer or a matrix of integers. 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 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. size 5.4.0 This function allows overloading for mlist type.