Date: Jun 16, 2013 5:14 AM
Author: Murray Eisenberg
Subject: Re: Multiplication by 0: non-zero in versions 8 and 9
In fact, the Mathematica behavior you observe in later versions, while

possibly disconcerting on strictly mathematical grounds, is reassuring

on software consistency grounds. Thus, the 9.0.1 documentation page

tutorial/ExactAndApproximateResults says:

"Whenever you give a number with an explicit decimal point,

Mathematica produces an approximate

numerical result [for a calculation involving that number]."

Personally, I would be unhappy if I did a calculation some of whose

numbers were approximate yet whose answer gave a misleading exact

answer.

On Jun 15, 2013, at 4:23 AM, Sotirios Bonanos

<sbonano@inp.demokritos.gr> wrote:

> Hello ,

>

> I have noticed that in all Mathematica versions <8, multiplying a real

or complex number by the integer 0 gives 0, but in versions 8 and 9

>

> Times[0, 0.567] gives 0.

>

> and

>

> Times[1.23 + I 2.45, 0] gives 0. + 0. I

>

> I don't know what prompted this change but it is definitely wrong: the

zero property of multiplication holds for real and complex numbers also

(see https://en.wikipedia.org/wiki/Multiplication#Properties) .

>

> Sotirios Bonanos

> http://www.inp.demokritos.gr/~sbonano/

>

---

Murray Eisenberg

murray@math.umass.edu

Mathematics & Statistics Dept.

Lederle Graduate Research Tower phone 413 549-1020 (H)

University of Massachusetts 413 545-2838 (W)

710 North Pleasant Street fax 413 545-1801

Amherst, MA 01003-9305