How to loop over the columns?

I have a matrix 101x19, I want to flip each column upside down to turn peaks in valley:

How I can do a loop?

 for i=1:length(data);   

 Flipdata(i,:) = 1.001*max(data,i-1)-(data,i);  

 end

Answer 1

[Walter Roberson]

 for i=1:size(data,2)
   Flipdata(:,i) = 1.001 * max(data(:,i)) - data(:,i); 
 end

or, with no loop,

Flipdata = repmat(1.001 * max(data), size(data,1), 1) - data;

and if you have R2016b or later

Flipdata = 1.001 * max(data) - data;

[Bruno]

Thanks Walter