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trying to display unusual matrix reboots calculator
06-28-2017, 10:58 AM
Post: #1
trying to display unusual matrix reboots calculator
I set a matrix, m to [[1 2 3],[4 5 6],[7 8 9]]
Then I was trying to see how the at() undocumented function works. So far, I'd only used it on vectors, so I wanted to try setting position in matrix to 4, thinking it might be the first element on second row, but instead it created a 4th row equal to one element (no longer a matrix).
i.e. m[4]=<99;
So this just added a 4th column/row and set it to 99, so it's no longer a square matrix.
When I put it in matrix mode and clicked on it, it rebooted the calculator.
Why did it do that?
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06-28-2017, 11:10 AM
Post: #2
RE: trying to display unusual matrix reboots calculator
Try using inter-digit comma's instead of spaces...
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06-28-2017, 01:29 PM
Post: #3
RE: trying to display unusual matrix reboots calculator
I did....CAS turns them into spaces.
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06-28-2017, 01:44 PM
Post: #4
RE: trying to display unusual matrix reboots calculator
According to xcas documentation, at() applies to a list. Here you want to address elements of a matrix, you can address the first element on second row by m(2,1): m(2,1)=<99
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06-28-2017, 05:16 PM
Post: #5
RE: trying to display unusual matrix reboots calculator
I know that, I'm just curious why displaying an array with 3 rows 3 wide and a 4th row only one wide causes the calculator to reboot?
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06-28-2017, 05:22 PM
Post: #6
RE: trying to display unusual matrix reboots calculator
Actually, i said that wrong. It's when I enter shift-matrix and select this malformed matrix, it causes the system to reboot.
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06-28-2017, 05:44 PM
Post: #7
RE: trying to display unusual matrix reboots calculator
Can you post the exact input and steps you were trying? I've been unable to see this reboot or get any malformed matrix stuff created.

Thanks!

TW

Although I work for HP, the views and opinions I post here are my own.
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06-28-2017, 06:29 PM (This post was last modified: 06-28-2017 06:31 PM by DrD.)
Post: #8
RE: trying to display unusual matrix reboots calculator
Your OP contains the corrupted matrix:
[[1 2 3],[4 5 6],[7 8 9]]

If, instead, you use:
[[1,2,3],[4,5,6],[7,8,9]]

You will see that your example has a syntax error, (mine works fine on my devices). Copy these and paste them into your command line to easily verify this for yourself ...

You can also use: m:=[[1,2,3],[4,5,6],[7,8,9]];
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06-28-2017, 09:17 PM
Post: #9
RE: trying to display unusual matrix reboots calculator
(06-28-2017 05:44 PM)Tim Wessman Wrote:  Can you post the exact input and steps you were trying? I've been unable to see this reboot or get any malformed matrix stuff created.

Thanks!

What I did was create a 3x3 matrix as in:
m:=[[1 2 3][4 5 6][7 8 9]];
....just use the matrix editor and you can make it.

Then when you type m, you should get:
m = 1 2 3
4 5 6
7 8 9

Next, execute the following command...make sure you are in CAS mode first...

m[4]=<99; // This is actually array_sto(99,at(m,3));

This will create m = [[1 2 3][4 5 6][7 8 9]99]
...which is a malformed matrix

You can go to shift-matrix
scroll to m[CAS] and click on it.
It will cause the reboot.

I'm not too worried about it at this point. Clearly I did an illegal operation. I was assigning a scalar to a matrix row for which space was not yet created.....so it's an illegal access, which is causing a reboot.
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