how I could execute the camera calibration code multiple times to get more than 3 selected points then find the average to get more precise result ...

NaN.

how I could execute the camera calibration code multiple times to get more than 3 selected points then find the average to get more precise result using loop

%display the image 
imshow('image.jpg');
%get the coordinate of three points of the image 
p=ginput(3)
%print + sign on the selected point 
hold on
plot(p(1,1),p(1,2),'+r')
plot(p(2,1),p(2,2),'+r')
plot(p(3,1),p(3,2),'+r')
%get real coordinate of selected point 
pg=input('Enter the real coordinate of selectd point')
%[1 2;7 2;5 6]
%calculate intrinsic matix
A=[pg(1,1),pg(1,2),1,0,0,0,0,0,0;
    0,0,0,pg(1,1),pg(1,2),1,0,0,0;
    0,0,0,0,0,0,pg(1,1),pg(1,2),1;
    pg(2,1),pg(2,2),1,0,0,0,0,0,0;
    0,0,0,pg(2,1),pg(2,2),1,0,0,0;
    0,0,0,0,0,0,pg(2,1),pg(2,2),1;
    pg(3,1),pg(3,2),1,0,0,0,0,0,0;
    0,0,0,pg(3,1),pg(3,2),1,0,0,0;
    0,0,0,0,0,0,pg(3,1),pg(3,2),1;]
b=[p(1,1);p(1,2);1;p(2,1);p(2,2);1;p(3,1);p(3,2);1]
x=A\b
 p=[x(1) x(2) x(3);x(4) x(5) x(6);x(7) x(8) x(9)]
 pr=p(1:3,1:2)
 [q,r]=qr(pr)
 r=r(1:2,1:2)
 l=r(1:2,2:2)
 %check the result
 title ('click on any point')
pt=ginput(1)
plot(pt(1,1),pt(1,2),'marker','O')
pc=r\[pt(1,1);pt(1,2)]
text(pt(1,1),pt(1,2),['(',num2str(pc(1,1)) ',' num2str(pc(2,1)),')'])
%matlab 2015b

Copied