how to add formatspec in writematrix

Dear matlab expert, I have these script

clc;clear; close all;


% Specify the folder where the files live.
myFolder = 'C:\ZTD\Wetz dan Dryz\DryZ\DryZ';
% Check to make sure that folder actually exists.  Warn user if it doesn't.
if ~isfolder(myFolder)
    errorMessage = sprintf('Error: The following folder does not exist:\n%s\nPlease specify a new folder.', myFolder);
    uiwait(warndlg(errorMessage));
    myFolder = uigetdir(); % Ask for a new one.
    if myFolder == 0
         % User clicked Cancel
         return;
    end
end
Allfile = fullfile(myFolder, '*.txt'); % Change to whatever pattern you need.
List = dir(Allfile);
for k = 1 : length(List)
    sites = List(k).name;
     num = readmatrix(sites);
num(:,end)=[];
      
% % %    sum up dryz+wetz in txt file
zwd1 = num(1:end,2);
zwd2 = num(1:end,3);
zwd3 = num(1:end,4);

% Seconds since 2000-01-01 00:00:00.0
 time_sec2000 = num(1:end,1);
% %  standard deviation values
%  stdev = num(1:2:end,4);
%   % mjd corresponding to 2000-01-01 00:00:00.0
  mjd20000 = 51544;
%   % Decimal days since 2000-01-01 00:00:00.0
  time_days = time_sec2000/86400;
%   % time vector in mjd
  MJD = time_days + mjd20000;
%   % compute decimal year
    [year, month, day, hour, minute, second] = datevec(MJD + 678942);
%     % time vector in decimal year
    YYF = decyear([year, month, day, hour, minute, second]);
%     PWV = zwd*0.15;
newdata = [MJD YYF zwd1 zwd2 zwd3];
%     %save data
writematrix (newdata,sites,'Delimiter','space')
end

I want my output file have formatspec using fprintf with MJD %15.8f YYF %14.8f and zwd1,zwd2,zwd3 %18.16f and I want to change the output filename to filename_out using writematrix. How can I do it?

[Rik]

If you have a strong opinion on the formatting, why don't you use fprintf instead of writematrix?

(just remember that MatrixWithData(:) will go through your array column by column, while you will read your text file row by row)