14 replies to this topic

[Chapas]

Hi guys.

I want to know how to solve a matrix like this one:



I know its possible because i already do solve it, but now my CP returns a Argument type...

How can i do it ?

Best regards [[]]

[Chapas]

18 views and nobody knows how to solve it with classpad?

hugz [[]]

[pan.gejt]

I found one solution only. I propose to solve this equation step by step. I rewrite the equation as A*B+C=D

1. multiply matrix A and matrix B and save the result as E (or anything else, depends on your priorities)
2. add matrix E and matrix C. This operation gives you system of 2 equations
3. use "solve" command for solving 2 equations (page 2.8.43 of user's guide for OS 3.05)

edited: TI-Nspire CAS allows quicker finding the solution. I used following syntax: solve(a*b+c=d,x,y). It gave me immediately the result x = -3 and y = 1.

Edited by pan.gejt, 06 December 2010 - 05:00 PM.

[300+Fan]

1. A*B (exe)
2. D-ans (exe)

solution:
x= -3
y= 1

[300+Fan]

10
8 ?

A:
22
12

B:
3
2

A*B =
2*3+2*2=10
1*3+2*2= 7

or am i wrong ?

[pan.gejt]

Classpad Warrior, JBB: you are wrong. How do you multiplicate the matrices?
300+Fan: you are right. The result is really 10 and 7.

[MicroPro]

The matrices in classpad are designed to be fast and memory-saving. So equations can't be put in them. And the classpad's solve function expects lists to be passed in, not matrices. But this doesn't mean that you can't solve it in one line:
Define this function:
define solveMat(A,B,V)=solve(matToList(A-B,1),V)
Usage (you can use 2D keypad to enter matrices instead of what i wrote here):
solveMat( [[2,2],[1,2]]*[3,2]+[×,[y]] , [7,8] , {x,y} )

Edited by MicroPro, 12 December 2010 - 06:07 AM.

[Chapas]

Micro PRO i didn't understood why you say to define the function?
Could you explain better?

MicroPro:
"define solveMat(A,B,V)=solve(matToList(A-B,1),V)
Usage (you can use 2D keypad to enter matrices instead of what i wrote here)
solveMat( [[2,2],[1,2]]*[3,2' />]+[×,[y]] , [7,8' />] , {x,y} )"

[MicroPro]

That way you don't need to do the solve in multiple steps.
It can be done in only one line of calculation.

Edited by MicroPro, 13 December 2010 - 08:55 AM.

[MicroPro]

The fact that ClassPad's solve function doesn't accept matrices as input is a technical limitation of ClassPad's expression evaluator implementation. ClassPad's CAS is able to solve those equations. Just you need some tricks like solve(matToList(A-B,1),V) to express your inputs in a way CP CAS understands.

And yes I think CASIO people should improve the solve function so that it directly accepts matrices.

By the way, is it now possible to define a functions with for, if , local variables and so on, on the classpad?

Almost yes, in OS 3 you can run normal programs from the Main interface.

Edited by MicroPro, 05 June 2011 - 08:54 AM.

[sma4t]

Thanks for suggesting the UDF, MicroPro  

The matrices in classpad are designed to be fast and memory-saving. So equations can't be put in them. And the classpad's solve function expects lists to be passed in, not matrices. But this doesn't mean that you can't solve it in one line:
Define this function:
define solveMat(A,B,V)=solve(matToList(A-B,1),V)
Usage (you can use 2D keypad to enter matrices instead of what i wrote here):
solveMat( [[2,2],[1,2]]*[3,2]+[×,[y]] , [7,8] , {x,y} )