MATLAB: Cellfun not working for cells contain cells

Question

Hi all,

I have a cell like this

K>> respCol
respCol =
  1×24 cell array
  Columns 1 through 5
    {3×1 cell}    {3×1 cell}    {3×1 cell}    {3×1 cell}    {3×1 cell}
  Columns 6 through 10
    {3×1 cell}    {3×1 cell}    {3×1 cell}    {3×1 cell}    {3×1 cell}
  Columns 11 through 15
    {3×1 cell}    {3×1 cell}    {3×1 cell}    {3×1 cell}    {3×1 cell}
  Columns 16 through 20
    {3×1 cell}    {3×1 cell}    {3×1 cell}    {3×1 cell}    {3×1 cell}
  Columns 21 through 24
    {3×1 cell}    {3×1 cell}    {3×1 cell}    {3×1 cell}

and each cell contains

K>> respCol{1}
ans =
  3×1 cell array
    [1034×2 double]
    [   2×2 double]
    [   6×2 double]

Now I'd like to make the arrays in each cell negative using cellfun, I tried this but didn't work

K>> cellfun(@(v) -v, respCol, 'un', 0)
Undefined unary operator '-' for input arguments of type 'cell'.
Error in beam>@(v)-v

So how can I do it?

Many thanks!

Answer 1

Your cellfun code simply says: negate the content of each cell in the outer cell array. However, that content is itself a cell array and matlab doesn't know how to negate a cell array. So you need another cellfun to go into these inner cell array:

cellfun(@(x) cellfun(@uminus, x, 'UniformOutput', false), respCol, 'UniformOutput', false)

Note that

cellfun(@uminus, cellarray)  %uminus is the function name of the negate operator -

will be faster than

cellfun(@(x) -x, cellarray)