[Octave-bug-tracker] [bug #50377] [octave forge] (statistics) pdist2 function returns complex results

[Georg Wiora]

Follow-up Comment #6, bug #50377 (project octave):

Sorry, it is so long ago I posted this sample that I forgot where I found the
problem. But the problem is a standard case in numeric. Therefore I recommend
the implementation of the suggested prevention for complex results.

An expression like _sqrt(x^2+y^2 - 2 * x * y)_ can always become complex if
the value of _x^2+y^2_ and _2 * x * y_ are equal in a range of _eps_. In this
case the argument of sqrt() may become negative and the result type changed
from double to complex.

This description may be used as a guide to constructing examples. Any numeric
pair of [x,y] is a good test case where the condition _x^2+y^2 == 2 * x * y_
analytically is true and _x~=0_ and _y~=0_ and I would suggest x~=y.



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