[racket] weirdness with complex numbers

Wolfram

http://www.wolframalpha.com/input/?i=roots+x%5E2+%2B+2*x+%2B+10


On Tue, Aug 7, 2012 at 6:28 PM, Matthias Felleisen <matthias at ccs.neu.edu>wrote:

>
> If it weren't against math conventions, I wouldn't mind seeing 1-i1 or
> 1/2+i2/3. But I am sure the people who produce Racket or Scheme or Lisp
> readers would hate me for that one, too. I think your students will need to
> cope, like all people who study sophisticated concepts (such as complex).
>
> Anyone know how Mathematica copes?
>
>
> On Aug 6, 2012, at 6:05 PM, Todd O'Bryan wrote:
>
> > I just discovered that the way you enter (and display) a number like
> >
> > 1/2 + (2/3)i
> >
> > in Racket (and Scheme, presumably) is 1/2+2/3i.
> >
> > I understand why that is, and can't think of what else to do, but has
> > anyone had students get confused because the form looks like the i is
> > in the denominator of the imaginary part?
> >
> > What's more potentially confusing is that 1/2+2i/3 is a legal
> > identifier in its own right.
> >
> > I'm working on a program that models basic algebra in the way that
> > high school students are taught to do it, and one of my self-imposed
> > rules has been that "math should look like math." In other words, I'm
> > trying to minimize the conversion gymnastics that students have to put
> > up with when they enter math in calculators or computer programs. In
> > that spirit, I'm not sure if it would be better to allow the
> > inconsistency with the way order of operations normally works or just
> > have students enter 1/2+(2/3)i (or 1/2+2i/3, maybe) and do the
> > conversion behind the scenes.
> >
> > Anyone have any thoughts or prejudices one way or the other?
> >
> > Todd
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>
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