Not the most effcient code but this should help your understanding. Also refer to this link for some of the different formating options for fprintf: https://www.mathworks.com/help/matlab/matlab_prog/formatting-strings.html
SomeIdentifier = 1;
boxMatrix = [1 2 3; 4 5 6; 7 8 9];
atomTypes = ['N' 'O' 'F'];
atomCounts = [7, 8, 9];
atomCoords = rand([20,3]);
disp(SomeIdentifier); %is just a variable equal to 1
disp(boxMatrix); % a 3x3 array containing numbers
disp(atomTypes); % a 1x3 array containing characters
disp(atomCounts); % a 1x3 array containing numbers
disp(atomCoords); % a 20x3 array containing numbers
vaspID = fopen('test.txt','w');
%is just a variable equal to 1
fprintf(vaspID,'%d\n',SomeIdentifier)
% a 3x3 array containing numbers
for ii = 1:size(boxMatrix,1)
fprintf(vaspID,'%d\t',boxMatrix(ii,:));
fprintf(vaspID,'\n');
end
% a 1x3 array containing characters
for ii = 1:length(atomTypes)
fprintf(vaspID,'%c\t',atomTypes(1,ii));
end
fprintf(vaspID,'\n');
% a 1x3 array containing numbers
for ii = 1:length(atomCounts)
fprintf(vaspID,'%d\t',atomCounts(1,ii));
end
fprintf(vaspID,'\n');
% a 20x3 array containing numbers
for ii = 1:size(atomCoords,1)
fprintf(vaspID,'%0.3f\t',atomCoords(ii,:));
fprintf(vaspID,'\n');
end
fclose(vaspID);
