Hi Dipen,
As far as I understand you want to read all the files in a specific folder with a for loop and do the calculations.
I wrote some code for you, you can check if it works correctly.
(Please don't forget to read comments.)
%% this part gives you the txt file name list in your folder
dirName = 'C:\Users\....\Desktop\NewFolder'; % folder path (please edit this as your own)
files = dir( fullfile(dirName,'*.txt') ); % list of all *.txt files
files = {files.name}'; % file names
%pre allocation for legend for the plot
legendString = cell(1,numel(files));
%% for loop
for i = 1:numel(files) % for loop for each file
% readtable
data = readtable(files{i});
% changing units
data{:,2:end}=data{:,2:end}*-1000;
% Calculation
data{:,7}=data{:,3}+data{:,5};
data{:,8}=data{:,4}+data{:,6};
data{:,9}=sqrt(data{:,7}.^2+data{:,8}.^2);
data.Properties.VariableNames([7 8 9])={'Px','Py','Ptot'};
% plot
figure;
plot(data.uxtop,data.Ptot); % plots the ith file data
hold on; % holds the plot for the next loop
legendString{i} = ['Mesh',sprintf('%d',i)]; % creates legend string as MeshX where X is a number
end % end for loop
%% legend,title,axis properties for plotted figure
legend(legendString);
title('Load displacement');
xlabel('ux (mm)');
ylabel('Total Load applied (P) kN');
xlim([0,10]);
ps. If you want to shorten your calculations section, please share an example data(txt) and desired output.
