On 11/1/09, Stavros Macrakis <macrakis at alum.mit.edu> wrote:
> The distinction is that abs is for when you want to *express* the concept of
> absolute value; cabs is for when you want to *change the form* of the
> expression to make it more explicit. This is similar to the noun/verb forms
> of integrate/limit/diff: 'integrate is to integrate as abs is to cabs. The
> consistent solution would be to change over to 'abs/abs.
Hmm, yes, that makes sense.
> declare(z,complex)$
> cabs(z+1) => sqrt(realpart(z)+1)^2+imagpart(z)^2)
>
> which is as expected. But abs(z+1) does the same thing, which it did not
> used to. So there is now no way to express the concept of "the absolute
> value of z" without writing it out in terms of real/imaginary components,
> which is horrible.
Yes, that seems bad. Typically, though, stuff gets changed because
of some other problem, of which we have now lost sight ...
I guess if we trawl through the CVS history we could discover
why it was changed?
best
Robert Dodier