MATLAB: How to split data text file with unequal elements in the row into several files

MATLABread data from text filesplit data fileunequal elements in the row

How to split data text file with unequal elements in the row into several files? the parts in file are separated by blank line. The last value in the first non blank line of the chain is a parameter for the name of the files that should be obtained. (Very first line is blank)
start ====================================================================
   169.454910       2.43834758              -3          80   167.000000    
   168.831055       1.62695873              -3        1360
   168.169083       1.72711039              -3        2640
   168.336090       2.58010888              -3        3920
   169.114761       3.06297684              -3        5200
   170.748550       2.64059544              -2          80   168.000000    
   168.722565      0.179684386              -2        1360
   166.820984      0.642302752              -2        2640
   167.385132       3.19096994              -2        3920
   169.737167       4.61249638              -2        5200
   172.051773       2.84667945              -1          80   169.000000    
   168.475510      -1.35426331              -1        1360
   165.393097     -0.431597352              -1        2640
   166.334351       3.77082968              -1        3920
   170.268417       6.19379234              -1        5200
   173.364777       3.05668116               0          80   170.000000    
   168.078079      -2.97351408               0        1360
   163.881104      -1.48867857               0        2640
   165.183487       4.32388353               0        3920
   170.708206       7.80115700               0        5200
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Best Answer

With just one textscan call. The test file is attached (you did not provide us with a sample file).
opt = {'CollectOutput',true};
[fid,msg] = fopen('test.txt','rt');
assert(fid>=3,msg)
C = textscan(fid,'%f%f%f%f%f',opt{:});
fclose(fid);
M = C{1};
D = diff([isnan(M(:,5));false]);
E = find(D<0);
B = find(D>0);
for k = 1:numel(B)
    F = sprintf('new %d.csv',M(B(k),5));
    csvwrite(F,M(B(k):E(k),1:4))
end
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