Optimize the weekly delay

clc; clear all; close all;

a=xlsread('C:\Users\Admin\Desktop\ArcSWAT_Install\26092021\Sir_RLR\RLR.xlsx');

car=a(:,2);

week_delay=14; %% I need to find optimum weekly delay number to give highest linear regression R square value

nvar=week_delay+1;

for j=1:nvar

p{j}=struct([]);

end

for w=1:nvar

p{w}=w:w+(99-week_delay-1);

end

for y=1:size(p,2)

combine(:,y)=car(p{y})';

end

input=combine(:,1:(size(combine,2)-1));

target=combine(:,size(combine,2));

[ShravanKumar Shivappa Masalvad]

I am using linear regression app to find the best weekly delay value to give highest optimum R square value.