Radical entries in non-CAS versus CAS

[Donna Roberts]

My question deals with a comparison of the non-CAS with the CAS versions.

 

On the non-CAS, set in RAD AUTO REAL, (radical 2) divided by 2 yields the decimal approximation.

On the CAS, set in RAD AUTO REAL, the same entry yields the “exact” entry stated again (which is what I would expect).

 

Yet when entering ¾ on both systems in AUTO, they both yield ¾ (the expected exact value).

 

Any idea why the radicals in the non-CAS version set to AUTO are responding differently than the CAS version set to AUTO? 
I guess I am thinking both handhelds would deal with this in a similar manner.

 

Donna

[Bryson Perry]

This is a CAS feature.  It will find the simplest radical form only on the CAS version of the Nspire. 

If you do sin(pi/4) you will get a different answer on both calculators as well. 

 

The Nspire CAS does things that the Nspire will not do, because of the Computer Algebra System (CAS).

 

The Nspire defaults to fractions for rational answers, but sqrt(2) is irrational and therefore will be a decimal approximation on the Nspire. 

 

Bryson 

----- Original Message -----

From: Donna Roberts

To: tins...@googlegroups.com

Sent: Saturday, March 08, 2008 6:14 PM

Subject: [tinspire] Radical entries in non-CAS versus CAS

My question deals with a comparison of the non-CAS with the CAS versions.

 

On the non-CAS, set in RAD AUTO REAL, (radical 2) divided by 2 yields the decimal approximation.

On the CAS, set in RAD AUTO REAL, the same entry yields the "exact" entry stated again (which is what I would expect).

 

Yet when entering 3/4 on both systems in AUTO, they both yield 3/4 (the expected exact value).

[Russell]

Surd (radical form) answers are symbolic, as are irrational values
such as pi and e. Non-CAS machines are not allowed to give symbolic
output. Rational numeric answers are OK, such as 3/4 as you stated.
CAS does not just referring to algebra based output but also any
symbolic notation.

Russell

On 9 Mar, 10:14, "Donna Roberts" <Don...@twcny.rr.com> wrote:
> My question deals with a comparison of the non-CAS with the CAS versions.
>
> On the non-CAS, set in RAD AUTO REAL, (radical 2) divided by 2 yields the
> decimal approximation.
>
> On the CAS, set in RAD AUTO REAL, the same entry yields the "exact" entry
> stated again (which is what I would expect).
>

> Yet when entering 3/4 on both systems in AUTO, they both yield 3/4 (the expected

[OrangeMath]

This is a weak area for TI. The low cost ($12 US) Casio ES series
(fx-300ES, fx-115ES, etc) shows symbolic answers. I use them as my
standard calculator and the TI's as special usage.

> > Donna- Hide quoted text -
>
> - Show quoted text -

[Donna Roberts]

On the non-CAS version (haven't tried it yet on the CAS):

If set to FLOAT, numerical values appear as one would expect on the
Calculator page -- but when graphing a scatter plot under "quick graph"
(under Data and Statistics) with a linear regression, the equation is
written with values rounded to the nearest integer.

If set to FLOAT 6 (default), numerical values (Calculator page) display 6
figures with a floating point, but the scatter plot under "quick graph" with
a linear regression writes the equation with six "decimal" values.

Both the Document Setting and System Setting were the same in each case.

Any comments on how to explain this one?

Donna

[Sean Bird]

That is fascinating, Donna.
I tried in on my CAS and it behaved similarly. I am a big fan of FLOAT.
However, it does result in fairly limited info for the D&S application.
From the 'About' page you can see that D&S was developed in conjunction with Fathom, whereas G&G has Cabri influence. On G&G you can modify the decimals easily with + and -.
Is that possible with on Data & Statistics? Time for more exploring or a request for the next OS.

Hey, I wonder which is everyone's most used application?
For me 1st place would probably be a toss up between G&G and Calculator, followed by perhaps another tie between Notes and L&S. Since I don't teach Stats, D&S comes in last place in the most used ranking.
I'm sure for my students, notes comes in last place right now.

- Sean

[hastern]

My TI-30 multiline (which I bought at Circuit City for $8) manages
this just fine.
I think my school is going to be getting them (the multiline 30s) as
our standard scientific calculator.

[Donna Roberts]

Is there a way to do a “frequency histogram” on the Nspire non-CAS (without the TI-84+ faceplate).

How about a cumulative frequency histogram?

 

These are do-able on the 84+, and several Algebra teachers have asked this question about the Nspire.

 

Thanks.

 

---

[Dr Stephen Arnold]

Hi Donna

Download the file named "add.tns" from the Files section of the Google Groups TI-Nspire site.

Put it into the MyLib folder on your computer or handheld.

Now when you create a new document and go to Catalog, choose the Library option, look for Add and look for two programs:

List2Table(list) takes a list of numbers and generates a frequency table from this in the form of a list called "Scores" and a list called "Freq".

In reverse, Table2List(list1, list2) takes list1 to be the scores and list2 to be the frequencies and generates the univariate list called "TableList" from this frequency table.

Obviously, to see these in the Table form, use L&S to show the two lists.

You can then use D&S to view all the available plots for the two forms for the data.

Steve

--

With best wishes,
Steve
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[OrangeMath]

Only the Casio ES models have Natural Display that makes sense to
students. 3 5/8 is far better than 3_5_8. TI has let us down on this
area, just as the display on the TI-84 was/is too low res. These are
design flaws. TI isn't perfect, but they have decent products with a
great deal of pro dev.

> > - Show quoted text -- Hide quoted text -

[Donna Roberts]

RE:  histograms from frequency tables and cumulative frequency histograms

 

Thanks for the info on the file “add.tns”.

 

The teachers were looking for a “built-in” procedure (similar to what was possible on the TI-84+), that would remain operational when the calculator was set (“cleared”) for Regents Exam testing.  Looks like manually manipulating the data and then preparing a regular histogram would be the only option.  We could use cumSum to some degree, but it’s the “frequency” that eludes direct entry.

 

Donna

 

---

[Dr Stephen Arnold]

This feature IS coming Donna - the programs are there to "tide us over" the next few months only.

There is an in-built function that can be used here - CountIf.

If you have a list of data, say List1 := {1,1,1,2,2,4,3,5,2,3,1}

Enter in column A of L&S.

Now in column B enter the values (manually) that occur (the "scores") scores:= {1,2,3,4,5}

Name column C, say, "freq"

In c1, type (I think), =CountIf(list1, a1) and fill this down.

I have just tried this and it does NOT seem to give correct results - I am going to report this as a bug - it is supposed to work.

The other option is the "frequency" command: works in a similar way:

frequency(list1, scores) in the gray formula entry line and this gives the frequency list - but always gives one extra entry at the end, usually 0. This is the number of results greater than the last score.

Don't ask me why...

Steve