converting a minute chart

Hi guys, i have a table with 6 columns and 4 million rows. Column1 shows the date and column 2 the time. Column 3 the opening price, column4 the max price, column5 the min price and column6 the closing price. The whole table presents a one minute chart. I want to convert this to a two minute chart in the following manner: two rows have to be combined(row1 and row2). Column 1,2,3 should have the values of row1. Column4 should contain the max value of row1 and row2. Column 5 should have the min value of row1 and row2. Column6 should have theclosing value of row2.

i used the following code:

x - your array (4e6 x 6)

n = ceil((1:size(x,1))'/2);
out = [x(1:2:end,1:3), accumarray(n,x(:,4),[],@min),...
               accumarray(n,x(:,5),[],@max),x(2:2:end,6)];
n = 2:100;
for jj = numel(n):-1:1
    n1 = ceil((1:size(x,1))'/n(jj));
    out{jj} = [x(1:n(jj):end,1:3), accumarray(n1,x(:,4),[],@min),...
                      accumarray(n1,x(:,5),[],@max),x(n(jj)-1:n(jj):end,6)];
end

bUT i get this error

out = [out(1:2:end,1:3), accumarray(n,out(:,4),[],@min),...
               accumarray(n,out(:,5),[],@max),out(2:2:end,6)]
Undefined function 'accumarray' for input arguments of type 'table'.

why is it not working?