Problem with timestamp and variables combination

Hello

I have a set of variables generated all the variables are matrixes of 400x1 double while the time stamp is 400x1 uint64 form. When I connect them side by side x=[time,X,Y,..Z] then the data X,Y,Z lose their decimal point and either round up or down. Also the save as ascii is not allowing me to save.

My question is how can I store the data into a variable that will have

timestamp X Y ....Z and then save it as ascii??

an example of the file that I want to get is

e.g 20120101.000000 X Y Z

20100101.000600 X Y Z

This is the code i used for extracting the date and changing in into the format I want

time = double(ncread(a,'time'));

time_offset=datenum(1900,1,1);

new_time=(time/24)+time_offset;

timestamp=datestr(new_time);

timestamp=datestr(new_time,'yyyymm.ddHHMM');

nt=str2num(timestamp);

timestamp=uint64(nt);

thank you very much