write 3 for loops in each other

I should write the program to get the positions x,y,z (lattice points) and then repeat these positions(lattice cube) in the x,y,z direction with the constant(lattice constant).my code is just working in one direction(x), how can I fix my code to work in all 3 x,y,z directions?

for k=0:o
    for j=0:m
          for i=0:n
             xpp(8*i+1:8*i+8,1)=xp+D*i;
             ypp(8*i+1:8*i+8,1)=yp+D*j;
             zpp(8*i+1:8*i+8,1)=zp+D*k;
       end
    end
end
%start
a=importdata('structure.xyz');
xp=a.data(:,1);
yp=a.data(:,2);
zp=a.data(:,3);
n=1;
m=1;
o=1;

xpp=xp;
ypp=yp;
zpp=zp;
for k=0:o
    for j=0:m
          for i=0:n
             xpp(8*i+1:8*i+8,1)=xp+D*i;
             ypp(8*i+1:8*i+8,1)=yp+D*j;
             zpp(8*i+1:8*i+8,1)=zp+D*k;
       end
    end
end

fileID = fopen('N.txt','w');
fprintf(fileID,'%s\n','silicon');
fprintf(fileID,'si %f %f %f\n',[xpp,ypp,zpp].');
fclose(fileID);

[JohnGalt]

what's D? what's the for loop at the start of your question (before '%start')? Can you give an example with some very small amount of data? are trying to create a grid starting from a specific point with a specific separation?

Answer 1

[Hamed Nobarani]

I was trying to get the unit cell of the structure which is contain positions of atoms and then expand it in 3 dimensions.

this is my code and answer to this question:

l=0;
s=0;
for k=1:o
         for j=1:m
             for i=1:n
                 nb=[xp+D*(i-1),yp+D*(j-1),zp+D*(k-1)];
                 pp(s+1:s+8,:)= nb;
                 s=s+8;
                 l=(l+1); 
       end
    end
   
end

[Rik]

The code below is equivalent to what you wrote, but should be slightly faster.

pp=zeros(o*m*n*8,3);%or: pp=zeros([o*m*n 1].*size([xp,yp,zp]))
s=0;
for k=1:o
    for j=1:m
        for i=1:n
            nb=[xp+D*(i-1),yp+D*(j-1),zp+D*(k-1)];
            pp(s+1:s+8,:)= nb;
            s=s+8;
        end
    end
end

l=o*m*n;

You should try to avoid l and o as variable names, because they look very similar to 1 and 0. It also looks like it should be possible to do this with meshgrid and reshape, which would avoid the loops.

[Hamed Nobarani]

Thanks Rik.

Sure,I got it.

Answer 2

[Karun Mathiazhagan]

Hello Hamed,

If my understanding is correct that you wish to create a 3-D grid of points similar to a lattice structure, the following MATLAB Answers post should be of use to you: https://www.mathworks.com/matlabcentral/answers/98191-how-can-i-obtain-all-possible-combinations-of-given-vectors-in-matlab