You don't say how you want x printed but you don't need num2str at all. In fact, if you just want a table of the ending array x, probably using dlmwrite is the simpler solution.
dlmwrite('output.txt', x, 'delimiter', ' ', 'precision','%10.5f')
Salt to suit on format, delimiter, etc., ... see
doc dlmwrite % for details
W/ low-level fprintf it'd be sotoo
fid=fopen('output.txt','w');
fprintf(fid,[repmat('%10.5f ',1,size(x,2)) '\n'], x.');
fid=fclose(fid)
NB: the .' transpose operation to get in row-major order and the explicit formatting.
doc fprintf % and friends for details/examples...
