You may have played/sung/heard a song without words in concert, in choir, and in a Sushi restaurant. Who hasn’t?!

Well here is a picture without words, only axes:

And here it is without JPG-encodingly unavoidable enhancements:

Bring this gallery to life by reproducing any aspect of the above.

(Truly, I’m still trying to recover the inequality that produced these pictures, from equipment more than 20 years bygone. Don’t make me cough up something new.)

This recipe might require more than 10 ingredients, or just the same two or three ingredients over and again.


1 Answer 1


This is a graph of

$\operatorname{sign}(-\cot x y +\cot y - \tan x + 2)$

enter image description here

  • $\begingroup$ You dog! Thank you for finding a more direct route than the original! Ain't mathematics simply beautiful?!?! $\endgroup$
    – humn
    Jul 26, 2017 at 22:47
  • 1
    $\begingroup$ How did you know!? $\endgroup$ Jul 26, 2017 at 23:20
  • 1
    $\begingroup$ Just a lucky guess! (For me, not you, you're a lucky find. So grateful . . .) $\endgroup$
    – humn
    Jul 27, 2017 at 0:59

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