Linsolve

[Francisco Zuñiga]

can ti-nspire non cas solve a system like this:

23a+45b+33c+44d=123
11a+22b+33c+55d=234
44a+33b+22c+11d=1234
55a+66b+55c+88d=23

yesterday i tried to solve it but it shows something like
42.c3,c3/34,.c3,2


thanks

[Jim Fullerenex]

I don't know exactly what function you are using... but, by either of the following (no sophisticated tricks, I guess) command you can get a perfectly good result free from the arbitrary constant "c3" (shouldn't have been present in the first place! )

solve(system(23a+45b+33c+44d=123,
11a+22b+33c+55d=234,
44a+33b+22c+11d=1234,
55a+66b+55c+88d=23),{a,b,c,d}) returns a boolean expression a=.. and b=.. and c=...

-------or-------------

linSolve(system(23a+45b+33c+44d=123,
11a+22b+33c+55d=234,
44a+33b+22c+11d=1234,
55a+66b+55c+88d=23),{a,b,c,d}) returns a list in the format {a value, b, c, d}

 

The CAS does quite good on this part, even with the lagrange multiplier system of equations.

Best Wishes,

Jim Fullerenex

2011/7/1 Francisco Zuñiga <franci...@gmail.com>

--
To post to this group, send email to tins...@googlegroups.com
To unsubscribe send email to tinspire+u...@googlegroups.com
For more options, visit this group at
http://groups.google.com.au/group/tinspire?hl=en-GB?hl=en-GB
The tns documents shared by group members are archived at
http://lafacroft.com/archive/nspire.php

[Nelson Sousa]

copy&paste the command you used here, you may have a typo somewhere.

[Joe]

Francisco asked if the NON CAS can solve the system. Perhaps I am
wrong because I don't have a non-cas nspire but I don't think the non-
cas version can do linear algebra. Again, perhaps I am wrong but I
think it would require the cas version.

[Nelson Sousa]

the non-cas can use the linsolve function, as well as solve systems by
computing the inverse of the system matrix and other methods.

The difference is that on the non CAS all coeffs need to be numbers
(real or complex) while the CAS also accepts undefined coefficients.

CAS refers to symbolic calculations, not algebra in general.

Cheers,
Nelson

[Lana Golembeski]

Well, the non-CAS can do matrices, right? Of course you have to do the math to use the matrices!

Lana

PS I have not used matrices on an Nspire...but I have on the TI 84.

--
To post to this group, send email to tins...@googlegroups.com
To unsubscribe send email to tinspire+u...@googlegroups.com
For more options, visit this group at
http://groups.google.com.au/group/tinspire?hl=en-GB?hl=en-GB
The tns documents shared by group members are archived at
http://lafacroft.com/archive/nspire.php

--
Lana Golembeski

AP Calculus Teacher

College Board Consultant

Minnetonka High School

Minnetonka, Mn

[Francisco Zuñiga]

i am using linsolve (despite format errors).. i get a result with "c1"

i used this function several times in the past; but something is wrong
now. This is my first time using a 4 var system but also i tried today
with a 3 var system with the same rare format (with "c") as result

A 2 var system was solved ok.


i am very frustrated because my problem was yesterday in a test :(


thank you!

On 1 jul, 13:08, Lana Golembeski <golem...@gmail.com> wrote:
> Well, the non-CAS can do matrices, right? Of course you have to do the math
> to use the matrices!
> Lana
> PS I have not used matrices on an Nspire...but I have on the TI 84.
>
>
>
>
>
>
>
>
>
> On Fri, Jul 1, 2011 at 12:00 PM, Joe <wjb...@yahoo.com> wrote:
> > Francisco asked if the NON CAS can solve the system.  Perhaps I am
> > wrong because I don't have a non-cas nspire but I don't think the non-
> > cas version can do linear algebra.  Again, perhaps I am wrong but I
> > think it would require the cas  version.
>
> > On Jul 1, 6:11 am, Francisco Zuñiga <franciscop...@gmail.com> wrote:
> > > can ti-nspire non cas solve a system like this:
>
> > > 23a+45b+33c+44d=123
> > > 11a+22b+33c+55d=234
> > > 44a+33b+22c+11d=1234
> > > 55a+66b+55c+88d=23
>
> > > yesterday i tried to solve it but it shows something like
> > > 42.c3,c3/34,.c3,2
>
> > > thanks
>

> > --> To post to this group, send email totin...@googlegroups.com> To unsubscribe send email totinspire+...@googlegroups.com

[Andy Kemp]

Can you post a picture of the result you get to the group as I have just checked this on my numeric software and don't get an answer in terms of a constant...  I'm wondering if it is possible you may have typed it wrong?

To post to this group, send email to tins...@googlegroups.com
To unsubscribe send email to tinspire+u...@googlegroups.com

[Epi van Winsen]

The linsolve works fine with the non CAS Nspire.

Use menu 3Algebra, 2 linear equations and the wizard.

Epi van Winsen

[Nelson Sousa]

If you're getting solutions with c1, c2, c3, etc. on your answer, you have a singular matrix and the system is underdetermined. Those c* are the parameters of the solutions.

That's why I asked you to copy&paste the command, I'm pretty sure you have a typo there.

Cheers,

Nelson