What is the origin/etymology of Matplotlib's symlog (a.k.a. symmetrical log) scale?
<p>This is not really a programming question. Rather a historical one...</p>

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<p>I am wondering about Matplotlib's <a href="http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.yscale" rel="nofollow"><em>symlog</em></a>
or "symmetrical log" scale:</p>

<ul>
<li>Is it a Matplotlib invention?</li>
<li>Has anyone seen a similar feature in another plotting tool?
A math text book?
Elsewhere?</li>
</ul>

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<p>For completeness, and as the documentation is a little bit on the short side:</p>

<p>In essence, <em>symlog</em> gives a linear scale below a certain threshold and a log scale above. This allows plotting a wide range of numbers (as does a log scale), including negative number and zero (which is not possible with a conventional log scale).</p>

<p>There are some examples <a href="http://matplotlib.org/examples/pylab_examples/symlog_demo.html" rel="nofollow">here</a> and <a href="http://stackoverflow.com/questions/3305865/what-is-the-difference-between-log-and-symlog/3513150#3513150">here</a>.</p>

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<p>As suggested by @Paul, I went ahead and asked the <a href="https://github.com/mdboom" rel="nofollow">original author</a> of the Matplotlib implementation. He "didn't invent the concept" but "believe[s] it was implemented on a user request". He couldn't find a reference in the Matplotlib mailing list, though.</p>

<p>Can anyone point to such a reference? It might be very insightful.</p>

<p>1) You would have to ask <a href="https://github.com/mdboom" rel="nofollow">mdboom</a>, who appears to have authored the relevant class (according to git blame), which is </p>

<p>2) SymmetricalLogScale.</p>

<p>Matplotlib has a github, and has been under version control for some time, so these questions are easily checked by reading the source + git blame.</p>

python matplotlib plot scale logarithm