Feature #15869: Add abs to Matrix

• Status: Closed
• Assignee: marcandre (Marc-Andre Lafortune)
• Target version: -

[bonafernando (Fernando Wolf Bona)]

While I was studying Markov Chain I had to find the maximum absolute value of the Matrix to divide the matrix in numbers from 0 to 1 to be able to make further analysis. Like this:

q = Matrix[ ... ]
max = q.to_a.flatten.map { |e| e.abs }.max
q = q / max

So this is the first of two features that I would like to contribute.

1. Matrix.abs
2. Matrix.max

[bonafernando (Fernando Wolf Bona)]

• Tracker changed from Bug to Feature
• Backport deleted (2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN)

[bonafernando (Fernando Wolf Bona)]

bonafernando (Fernando Wolf Bona) wrote:

While I was studying Markov Chain I had to find the maximum absolute value of the Matrix to divide the matrix in numbers from 0 to 1 to be able to make further analysis. Like this:

q = Matrix[ ... ]
max = q.to_a.flatten.map { |e| e.abs }.max
q = q / max

So this is the first of two features that I would like to contribute.

1. Matrix.abs
2. Matrix.max

PR: https://github.com/ruby/ruby/pull/2199

[marcandre (Marc-Andre Lafortune)]

• Assignee set to marcandre (Marc-Andre Lafortune)

[shevegen (Robert A. Heiler)]

Interesting. Not sure if this has to do with Markov Chain per se, but for storing state
through automata (in bioinformatics), hidden markov models are also used. Perhaps
extending Matrix may be beneficial in general (for ruby as a larger ecosystem;
curiously enough, the third most often downloaded gem is diff-lcs, which is probably
useful in a variety of different applications; I came to it indirectly through Hamming
and Levensthein distances).

[marcandre (Marc-Andre Lafortune)]

• Status changed from Open to Closed