More efficient row removal

Hi all,

From subsets of a matrix I want to remove all first columns containing a date value that is 'night'. The matrix is very large (>300000 entries) and I would like to make a faster way.

 A{i} -11.238        42.72       11.518          460          777
      -11.217        42.72       11.518          464          777
      -11.176        42.72       11.518          457          777
      -11.133        42.72       11.518          465          777
      -11.092        42.72       11.518          463          777

morning=6;
evening=18;
ab = find(morning > hour(A{i}(:,1)) & hour(A{i}(:,1)) >
evening);
[ac,PS] = removerows(A{i},'ind',ab);
disp(ac);
disp(datevec(ac(:,1)));

So this works well, but slow.

Any suggestions?

Kind regards and thanks in advance, Daan

[Matt Kindig]

Can you convert A to a numeric matrix (rather than a cell array)? That might help.

Also, do you need the PS output of removerows()? Could you just use elementary matrix operations?

How is 'hour' defined? Is this a matrix or a function?