11 replies to this topic

[epaloco]

[B]Hi,does anyone know how to invert a matrix with literals I mean is it possible to invert a for example 4X4 matrix with literals in their rows or columms?

thanks very much,
Alejandro.

Please try to answer this I need to invert lot of matrix to make Laplace transforms,,,simple differential equations,,but big trouble inverting non numbers matrixs!!!!

In spanish....

alguien sabe como invertir una matriz con letras ?o sea supongamos que tiene una letra adentro de la matriz?? como se hace eso?algun truco o programita que sepan??
gracias
Alejandro.

[BiTwhise]

There are two commonly used methods for finding the inverse of a matrix.
1) by using co-factors
2) by using elemtary row operations

The latter is often used by compter software, since it is computationally cheaper (most often), but it is not suitable for a symbolic approach.

The first works fine with symbols, but it gets really heavy with bigger matrices..

if you a matrix A <> 0, the inverse is defined as 1/det(A) * adj(A)

Where
adj(A) := adjoint matrix of A = Transpose of the matrix of cofactors of A


example:
A =
| 1 1 1 |
| 1 2 3 |
| 1 4 9 |


det(A)= 6 - 6 + 2 = 2

matrix of cofactors=
| 6 -6 2 |
| -5 8 -3 |
| 1 -2 1 |

therefor
adj(A) =
| 6 -5 1 |
| -6 8 -2 |
| 2 -3 1 |


inv(A) = adj(A)/det(A) =
1/2 *
| 6 -5 1 |
| -6 8 -2 |
| 2 -3 1 |



This is just a simple example to give you the idea.. doing it symbolically is just more work than I can be bothered to do now
Perhaps this was not what you were looking for though?
I assume you probably knew this already

[betoe]

Epaloco wants to make it in the AFX using variables, something like "A" or "A-1" etc...

[BiTwhise]

Hmm..
That's gonna be hard, and terrebly slow.. if even possible :/

Is it a non-pluss model?
The AFX2.0Plus has support for matrices in the CAS module..

[epaloco]

yes but you are not allowed to enter literals in the plus either...

[RAM-SeS]

Mmmmm i have a little problem i don't have the plus... but i just put the CAS2 but i still can't use matrix in the cas !

Is it exclusive for the plus ? (i don't think so!) how do u use it ?

(me podeis contestar en espa?ol)

[betoe]

Well for view the differences between the AFX 2.0 and 2.0 Plus visit the mohamed site, if i'm ok (watch the link page of this forum) the URL is:
www.algebrafx.earthforge.com

In spanish:
Hola bienvenido al foro, cualquier duda que tengas tal vez yo podr?a ayudarte. A como s? en ninguna calculadora casio de los modelos Algebra FX se pueden introducir variables en matrices.

[RAM-SeS]

Then now, do FX 2.0 users have to buy the FX 2.0 PLUS ?

The answer is NO, no one would really need all these add-ins at the same time, we could use only the ones we need and keep living, and as for the CAS and ALGEBRA updates, we could only hope that they produce them as new add-ins.

(from the page u said)

The AFX2.0Plus has support for matrices in the CAS module..

(bitwhise)

List, Matrix, and Vector functions have been added to the CAS operation.

(from http://www.casio.co..../algebra_fx20/)

The problem is that i can't find out how to use it!
if any1 could helpme


thank u

[Mohamed]

CAS 2 that CASIO has on their site has no matrix operations available.
If you read what I said in my site carefully, this is only included in the FX 2.0 PLUS.
They don't want to release a similar CAS to that of the PLUS or their would be no pint to get it.

[RAM-SeS]

can anyone get it out from the plus and put it in cfx form. I mean using a prog like gcomm to send the exe to the pc !

Thank u !

[CrimsonCasio]

is that possible? i never considered it... however, I dont think casio would like that to much and it might be illeagle...

[coco]

English/Ingl?s

Hi

It is possible to enter symbolic matrices in AFX 2.0+ but this must be done in CAS mode (usually option 9 in main menu). Matrices entered un RUN-MAT mode (option 1 in main menu) must not be symbolic and are not recognized in CAS mode.

In CAS mode you can invert a symbolic matrix with no problems, you can also transpose, find determinants and other operations as if you were working with numeric matrices. One disadvantage is that, in CAS mode, you don't have the matrix editor that appears when you press F1 in RUN-MAT mode so you must enter the matrix (no pun intended) as follows:

A 2x2 symbolic matrix:
1 x
2x -x/2

[[1,x][2x,-x/2]]->A "EXE"

then to invert matrix A

A"SHIFT") "EXE" (the X with the little -1 over the ")" key)

And that's all

One more thing: AFX 2.0+ cannot do symbolic eigenvalues or eigenvectors even in CAS mode.

Coco

Espa?ol/Spanish

Es posible ingresar matrices simb?licas en la AFX 2.0+ pero esto debe hacerse estando en el modo CAS (opci?n 9 del men? principal). Las matrices definidas en el modo RUN-MAT (opci?n 1 del men? principal) no pueden ser simb?licas y no son reconocidas por el modo CAS.

En el modo CAS se puede invertir una matriz simb?lica sin problemas. Tambi?n se puede transponer, hallar determinantes y hacer cualquier otra operaci?n como si se tratase de matrices num?ricas. Una desventaja es que en el modo CAS no tienes el editor de matrices que aparece cuando presionas F1 en el modo RUN-MAT por lo que debes ingresar la matriz as?:

Una matriz simb?lica de 2x2:
1 x
2x -x/2

[[1,x][2x,-x/2]]->A "EXE"

luego para invertir la matriz A

A"SHIFT") "EXE" (la X con el -1 peque?o que est? sobre la tecla ")")

y eso es todo

Una cosa m?s: La AFX 2.0+ no puede calcular simb?licamente valores propios ni vectores propios, ni siquiera en el modo CAS

Coco