# How can I save the eigenvalues of a 1000x1000 COE matrix and 500x500 COE matrix in the same file?

I have generated eigenvalues of '1' 1000x1000 matrix of CircularOrthogonalEnsemble and saved it in a csv file using Export. Now I want to save eigenvalues of another '1' 500x500 matrix of COE in the same csv file. How can I do that? In total, I want 100 csv files of eigenvalues combining eigenvalues of both the 500x500 matrix and the 1000x1000 matrix

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As a simpler example, I have two lists: the first one has integers and the second one has real numbers in arrays of different sizes.

alist = RandomInteger[{-10, 10}, {10, 10}];
blist = RandomReal[{-1, 1}, {5, 5}];


Let's say you have written a csv file using:

fName = "C:\\test.csv";
Export[fName, alist, "CSV"]


You can now open the file for appending as a stream first.

strm = OpenAppend[fName]
Export[strm, blist, "CSV"]


Don't forget to close the stream.

Close[strm]


To import back in Mma:

clist = Import[fName, "CSV"]
clist // TableForm