I don't want to seem I turned the rant mode, on, but:
Last statement makes so little sense as saying the "expected" thing is that
4 sqrt
should return a tuple #(2.0 -2.0) because it happened before we had computers....
The "Principle of Least Surprise" should be taken in the context of the Smalltalk language history. For an argument based in mathematical package, if you open a "R" (a statistical package based in ATT's S language) repl and do the similar call you get:
> sqrt(-2)
[1] NaN
Warning message:
In sqrt(-2) : NaNs produced
Specific mathematical packages like Maxima, Scilab and Octave have flags to control the behaviour for this case.
HTH
Em 12/08/2009 12:11, Ken.Dickey < [email protected] > escreveu:
KenD> > Currently:
> >
> > -1 asComplex isNumber --> true
> > ?1 asComplex isNumber -> true
> > -1 asComplex < 1 asComplex --> error
> >
> > -4 sqrt --> error
Igor Stasenko >
> and it should.
> Not many people using a complex numbers. And -4 is an integer number,
> not complex number (i hope this non-objectionable?). And sqrt function
> is not defined for real/integer numbers < 0 ,and should lead to error,
> period.
> If you change this behavior, some of code will fail to work correctly
> , definitely.
> But you are free to use something like:
> -4 asComplex sqrt
So you prefer (1 asFraction / 2) -> 1/2 , where (1/2) gives an error because 1
and 2 are not fractions?
(-1 s qrt) is the definition of 1i .
Other dynamic languages I use [Scheme, Lisp] which define complex numbers all
give square roots of negative numbers.
I am trying to approach the Principle of Least Surprise here. Computers are
very bad at math, but we have learned painfully to work around this. I
would like pre-computer high school math to "just work". IEEE Floats only
guarantee the wrong answer fast, IMHO.
I would like square roots of negative numbers to work like they did before I
got a computer! 8^) 8^O 8^{
Cheers,
-KenD
_______________________________________________
Pharo-project mailing list
[email protected]
http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
_______________________________________________ Pharo-project mailing list [email protected] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
