i have a column matrix [23; 34;22;13]. i need to create set of column matrixs ,which give 1 and -1 in numbers if the next number is less than and larger than.

A=[23; 34;22;13] output matrixs=[1;-1;-1],[-1,-1],[-1]

Answer 1

[Guillaume]

One possibility:

A = [23; 34; 22; 13];
out = arrayfun(@(idx) sign(A(idx+1:end) - A(idx)), 1:numel(A)-1, 'UniformOutput', false)
celldisp(out)

[shashika iresh]

please the code you give only a one matrix. please sea the image i send. it should be like that only. if you can please help.it is defficult to explain. so i have send a picture.

thanks

[Guillaume]

The example I showed outputs a cell array of 3 matrices. Exactly as you asked. I even included a celldisp call to show that the cell array contains the 3 matrices you want.

>> celldisp(out)

out{1} =

       1
      -1
      -1

out{2} =

      -1
      -1

out{3} =

      -1

[shashika iresh]

thanks a lot

[shashika iresh]

how can i take the summation of all output matrix elements.

[Guillaume]

They're different size. How do you want to sum them up?

[shashika iresh]

i want to take the sum of each elements of all the out matrix's . please help.

[shashika iresh]

for above output, [out(1)=(1-1-1)=-1, out(2)=-1-1=-2, out(3)=-1]:all sum=-1-2-2=-5. like that

[Guillaume]

arrsum = cellfun(@sum, out);
totalsum = sum(arrsum)

will do

[shashika iresh]

Thanks a lot

Answer 2

[Atsushi Ueno]

I have modified the last answer after getting your comment.

A = [23; 34; 22; 13];
B = sign(diff(A));
matrixs = {0};
for i = numel(B):-1:1
  matrixs = {B(i:end), matrixs{:}};
end