13 03 12 00 00 0.0000000 0 7 G05 G16 G21 G25 G29 G30 G31*
fid=fopen('filename.txt','r'); % open file
l=fgetl(fid); % get header line to parse
[n,~,~,nxt]=sscanf(l,[repmat('%*f',1,7) '%d']); % find n, number of sat's, next place in string
fmt=[repmat('G%d ',1,n-1) 'G%d*']; % build format string for the sat's
s=sscanf(l(nxt:end),fmt); % read sat no's
d=cell2mat(textscan(fid),repmat('%f',1,6))).'; % read and reshape data