Posted by KenDickey on Aug 15, 2009; 4:45pm
URL: https://forum.world.st/if-at-first-you-dont-succeed-tp1303541.html

> i disagree.
> As i said earlier, a square root function result is not defined for
> arguments less than zero in real (R) set.

Right, only for complex (C).  R < C   [C contains R].

> This is strictly mathematical behavior, same as division does not
> defines a value for zero.

My _Elementary Functions_ book has a nice section which defines the square
root of -1 to be 1i.

I pick up _Handbook of Physical Calculations_ and find an entire section on
the mathematics of alternating current which uses complex math exclusively.

I see why, given Smalltalk's history, one does not wish to change the way
things are done.  This is a bit different from implying complex mathematics
is not mathematics.

> Just think about, how many code i could break, if i return an Infinity
> (or something like this) as a result of division by zero instead
> of signaling error.

My recollection (again, not to be trusted) is that Java returns an IEEE
infinity rather than throwing an exception.  I do not recommend this either,
which is why I am puzzled by #ln returning a NaN.

Again, my recommendation is that the current Complex implementation be removed
from Pharo-Core.

Reluctant as I am to suggest it, an allowComplexResults global preference
could be used, with the usual "Here Be Dragons" warnings.  Such a preference
would clearly state that it is to allow functions like #ln and #sqrt to
return complex results and would only be settable if a Complex number package
was loaded.

Cheers,
-KenD

PS:  My apologies, but my laptop died and I am borrowing time on someone
else's computer.  I intent to browse "sqrt senders" when I get another
machine to see what code is breaking.

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