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23 lines
1.2 KiB
Plaintext
23 lines
1.2 KiB
Plaintext
ndiff is a utility for comparing putatively similar files, ignoring small
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numeric differences. The utility is written by Nelson H. F. Beebe and
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covered by the GNU General Public License (GPL), version 2. It may be
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built with arbitrary precision support (more powerful) or using built-in
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floating point precision, see Makefile.
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Assessing the consistency of a numerical program run in multiple
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environments (operating systems, architectures, or compilers) can be a
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difficult task for a human, as small differences in numerical output values
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are expected. File differencing utilites, such as diff(1), will generally
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produce voluminous output, often longer than the original files.
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ndiff solves this problem. Taking two text files expected to be
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identical, or at least numerically similar, it allows to specify absolute
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and/or relative error tolerances for differences between numerical values
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in the two files, and then reports only the lines with values exceeding
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those tolerances. It also tells by how much they differ. A simple example:
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% ndiff --relative-error 1.0e-3 test019.txt.1 test019.txt.2
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### Maximum relative error in matching lines = 8.64e-51 at line 129 field 4
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WWW: http://www.math.utah.edu/~beebe/software/ndiff/
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