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dpb
Posts:
8,715
Registered:
6/7/07


Re: numel or length, which is better?
Posted:
Apr 16, 2013 3:39 PM


On 4/16/2013 2:16 PM, dpb wrote: > On 4/16/2013 2:03 PM, Hesham Ismail wrote: ...
>> length calculate the number of column whereas numel calculate the number >> of element > ... > > Not necessarily... > ...
> As noted in earlier response LENGTH() is max(size(x)) for any x whereas > NUMEL() is prod(size(x)) > > If one is interested in rows or columns (and often are) then have to ask > for the size of the pertinent dimension to be certain....
And to belabor the point but to drive it home...
>> D=rand(2,3,5); >> length(D) ans = 5 >> max(size(D)) ans = 5 >> size(D) ans = 2 3 5 >>
I've used utility functions on occasion for nrows and ncols as syntactic sugarthey're trivial to write, of course
function nr=nrows(x) % N = nrows(A) returns the number of rows, N, in array A.
nr=size(x,1);
function nc=ncols(x) % N = ncols(A) returns the number of cols, N, in array A.
nc=size(x,2);




