use Math::MatrixReal;

#update:
Math::MatrixReal->new_from_string(<<'MATRIX');
[ 0 48.23 17.90]
[ 48.23 0 49.58]
[ 17.90 49.58 0]
[ 59.62 52.04 65.80]
[ 62.20 56.02 68.82]
[ 35.37 37.87 36.52]
[ 27.33 50.73 31.85]
MATRIX

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Then all your stuff reduces to finde the appropriate indices to iterate over. For the more exotic itarations 
use Algorithm::Combinatorics;

[download]
For the column sums remember that with the matrix X and the rows(X)-vector I of one X'1 gives the sums for every column.

In reply to Re: extracting and using values from a matrix file by dokkeldepper
in thread extracting and using values from a matrix file by Angharad

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