Dear every one,

I have a problem with classpad300, when I try to find the inverse of a 4 by 4 matrix I receive an error (insufficient memory)! Note that the matrix elements are variables i.e. a,b,c,d,...etc. not numbers.

Isn't 500KB of working RAM enough for this simple operation? Can any one lead me to a way finding that inverse of 4x4 MAT.

Thanks.

# Classpad Error

Started by
ECE
, Feb 08 2008 02:37 PM

6 replies to this topic

### #1

Posted 08 February 2008 - 02:37 PM

### #2

Posted 08 February 2008 - 02:42 PM

Hello M. Yasser and welcome to the UCF.

I've heard of problems with inverse matrices before on the ClassPad. Maybe it's because you're using an old OS. I think you need to upgrade the OS.

I've heard of problems with inverse matrices before on the ClassPad. Maybe it's because you're using an old OS. I think you need to upgrade the OS.

### #3

Posted 08 February 2008 - 02:59 PM

I'm here to get help specifically about o.s v.3.0 .

### #4

Posted 09 February 2008 - 11:23 AM

If the entries are simply variables (as opposed to plynomials or the like) (i.e., letters standing for any particular number) then what you want, it seems to me, is the general method for finding inverses for matrices of that size. (Of course, not all matrices have inverses). So why not just find a book that shows how to invert a 4 x 4 matrix? For example, a method for inverting a 3 x 3 matrix is shown here:

http://www.purplemat...es/mtrxinvr.htm

If your "variables" are really polynomials or other expressions rather than just letters standing for numbers there seem to be specialized methods for finding inveres:

http://ieeexplore.ie.......1727&code=4

Lance

http://www.purplemat...es/mtrxinvr.htm

If your "variables" are really polynomials or other expressions rather than just letters standing for numbers there seem to be specialized methods for finding inveres:

http://ieeexplore.ie.......1727&code=4

Lance

### #5

Posted 09 February 2008 - 12:45 PM

The problem is not with the method I'm sort of familiar with Linear Algebra; but the method that that ClassPad calculates symbolic math maybe the problem?

Note that the variables i.e. (a, b, c, d, e, ?etc)where all cleared before the procedure so as to get the results in symbolic form (to derive a general form of an equation).

Note that the variables i.e. (a, b, c, d, e, ?etc)where all cleared before the procedure so as to get the results in symbolic form (to derive a general form of an equation).

### #6 Guest_gatico_*

Posted 11 February 2008 - 03:52 AM

I'm receiving the same message when I try to do a "hard" integration, for example:

∫(x+(36*x+3)/(2*x+tan(2*x)),x)

I tried it on Maple and on the TI-89 and the solved it withouth any problem, but I don't know why I'm receiving this message.

∫(x+(36*x+3)/(2*x+tan(2*x)),x)

I tried it on Maple and on the TI-89 and the solved it withouth any problem, but I don't know why I'm receiving this message.

### #7

Posted 11 February 2008 - 02:48 PM

some one post to me the folowig,

A hard integration may require more specialised algorithms. I don't think matrix inversion requires different algorithms according to the size of the matrix - just a scaling up. So whilst I don't know the reason for failing with an integration problem (it could be stack size, but it could be an algorithm failure), I suspect that the reason for the matrix inversion failure is keeping track of all the symbols, and where they are located in the final matrix, i.e., I think the memory outage occurs with the parsing stacks (there is just too much to keep track of within that provided stack).

A hard integration may require more specialised algorithms. I don't think matrix inversion requires different algorithms according to the size of the matrix - just a scaling up. So whilst I don't know the reason for failing with an integration problem (it could be stack size, but it could be an algorithm failure), I suspect that the reason for the matrix inversion failure is keeping track of all the symbols, and where they are located in the final matrix, i.e., I think the memory outage occurs with the parsing stacks (there is just too much to keep track of within that provided stack).

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