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From: Helen on 11 Feb 2007 19:41
On Feb 11, 2:33 pm, "JBGM" <Literatron...(a)gmail.com> wrote:
> Before someone answers that I should use Maple or Mathematica (how do
> you think I obtained the complex root?), here goes the explanation:
> I'm a professional mathematician who wants to use a CAS in a handheld
> device for a research project. I have to do massive symbolic
> computations

What do you mean by "massive symbolic computations"?
You cannot do massive symbolic computations on a dinky little
calculator.
Besides, the example you give is hardly an example for a "massive
symbolic computation"...

> while I move across large library's shelves, so carrying
> a laptop is simply annoying.

I am sorry, but I have to ask: Do you have to do these calculations
while hanging upside down from those shelves? If so, then I can
understand your request, but I find your line of work, interesting, to
say the least. If not, then I have trouble understanding your
requirements. If you really are a mathematician, and if you really
need to do "massive symbolic calculations", then a calcultaor is not
the right tool. As a mathematician, you should also be more concerned
about using a tool that can do the job you need, than with the
"annoyance" of having to carry a 3-pound laptop, in my humble
opinion...



From: Virgil on 11 Feb 2007 20:06
In article <oDMzh.10692$lM4.673(a)reader1.news.saunalahti.fi>,
"Veli-Pekka Nousiainen" <DROP_vpn(a)dlc.fi> wrote:

> "Veli-Pekka Nousiainen" <DROP_vpn(a)dlc.fi> wrote in message
> news:UiMzh.10681$yD4.9411(a)reader1.news.saunalahti.fi...
>
> I tried with checking that REALASSUME list had X and Y defined
> and that the last flag in the Flag Browser said the Complex Vars are allowed
> Then I tried:
> 3: ['LN(Z)+SIN(Z)+Z^2']
> 2: ['Z']
> 1: [(-1.,-1)]
> MSLV
> and I got (using FIX 2 setting to ease up the writing here)
> 1: [(-1.39,-0.98)]
>
> What do you say to that folks?

I wasn't even aware of MSLV. Thanks.
From: JBGM on 12 Feb 2007 09:53
Helen, if you MUST know 8-) here is more information:

> What do you mean by "massive symbolic computations"?
> You cannot do massive symbolic computations on a dinky little
> calculator.

'Massive' is manipulation of large polynomials (multiplication,
integration, division) to find irreducible representations. Yes, it
can be done in a handheld. Yes, it is quicker in a full-size computer.

> Besides, the example you give is hardly an example for a "massive
> symbolic computation"...

But just an example of the device's mathematical capability.

> I am sorry, but I have to ask: Do you have to do these calculations
> while hanging upside down from those shelves? If so, then I can
> understand your request, but I find your line of work, interesting, to
> say the least. If not, then I have trouble understanding your
> requirements. If you really are a mathematician, and if you really
> need to do "massive symbolic calculations", then a calcultaor is not
> the right tool. As a mathematician, you should also be more concerned
> about using a tool that can do the job you need, than with the
> "annoyance" of having to carry a 3-pound laptop, in my humble
> opinion...

I'm comparing a new method to do something (sorry... confidential
information) with existing literature. I have about 300 books in my
list for which there is no digital version. I could: (i) checkout
books by the dozen and carry them in a cart to my office, or (ii) I
could find the two pages am interested of each book without leaving
the shelves and do the test I'm interested in. I will save many hours
by doing the test on the spot. That's all the info I'm giving. The
world is fairly rich and complex, so be less surprised when you do not
understand causes and reasons; you might be missing the rest of the
iceberg ;-)

The algorithm is simple: if (estimated hours saved * personal labor
hour cost per hour) - (cost of calculator + time invested in training
* personal labor hour cost per hour) > 0 then go calculator. So far, I
go calculator. BTW TI-89 seems to have superior symbolic manipulation
capabilities FOR MY PURPOSE. Look at http://technicalc.org/tifaq/?tivshp.htm.
HP 50g seems fairly superior in numerics.

From: John H Meyers on 12 Feb 2007 13:24
On Sun, 11 Feb 2007 14:33:10 -0600, JBGM wrote:

> I have a very simple problem in which the HP 50g fails miserably

User error :)

> Should I use another function?

Getting warmer :)

> SOLVE('LN(X)+SIN(X)+X^2=0', 'X')
> Solve(LN(X)+SIN(X)-X^2=0, X) [different EQ on TI]

['LN(X)+SIN(X)+X^2=0']
['X']
[(0,0)]
MSLV ==> [ (.490672430034,0.) ]

['LN(X)+SIN(X)-X^2=0']
['X']
[(0,0)]
MSLV ==> [ (.877484133454,-.255824885891) ]

Better or different initial guesses
will yield faster or additional roots.

[r->] [OFF]
From: Marcin Witek on 12 Feb 2007 14:21
Steen Schmidt wrote:
> Finding the real root 0.490672... takes 14.9 seconds on the TI, while
> ROOT does it in 1.1 seconds on the HP. Both only return one root
> without an estimate on how many other potential roots exist. I think
> the HP is better in this case (same features but faster performance).

What guess value for ROOT are you using on HP?

Wit
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