[WP34s] Possible problem with matrix inversion



#2

I just tried the matrix inversion command with a simple 4x4 matrix. Calling M-1 directly from the keyboard makes the calculator shut down (!). Sometimes the VERS screen is displayed instead.

However, if the same M-1 command is used from within a program, everything works fine:

  001 LBL A
002 M-1
003 END
Used this way, the command is executed as expected. The same applies to M-1 calls from the library, e.g. the matrix editor MED.

All this applies to Version 3.1 3325 as well as the new 3.2 3350 (updated a few minutes ago). So, is it the firmware or is there a problem with my hardware?


Dieter


#3

Quote:
I just tried the matrix inversion command with a simple 4x4 matrix. Calling M-1 directly from the keyboard makes the calculator shut down (!). Sometimes the VERS screen is displayed instead.

Have you tried it on the emulator, too?

I just did it (also 4x4) and had no problems.

Franz


#4

The emulator works fine. It's "the real thing" that behaves that way.

Dieter

#5

Hmmh, I just tried with build 3335 on my "real thing" and everything worked fine.

My matrix (chose some arbitrary values without thinking much):

 1   2   3   4
0 1 4 9
7 6 5 4
1 0 -1 1
How's your matrix looking?

d:-)


#6

Quote:
How's your matrix looking?

It's looking great, of course. 8-)

Since the early Eightes I'm using a simple test matrix, taken from a book on numerical algorithms I bought back then:

      5   7   6   5                  68 -41 -17  10
7 10 8 7 -41 25 10 -6
A = 6 8 10 9 Inverse = -17 10 5 -3
5 7 9 10 10 -6 -3 2
This, as well as a 4th...6th order Hilbert matrix, usually is the first thing I try with new matrix software.

But I do not think the matrix itself is the reason for this strange behaviour. I fear something went wrong with the crystal/IR upgrade and it's actually a hardware problem. The same BTW happens with the LINEQS command. I just wonder why everything is fine as soon as the same functions are called from within a program. Strange.

Dieter


#7

I fear you're right. Your matrix inverts on my calculator just fine. I can't tell you, however, how the quartz / IR shall effect your calculations - maybe Marcus knows more about that particular case?

d;-)

#8

Dieter, I suspect your hardware is broken. What does BATT say? Can you switch to SLOW mode and try again?


#9

BATT returns 2,9 V, and after SLOW the same thing happens: M-1 turns the device off, and in some cases it displays the VERS message.

Dieter

Edited: 5 Jan 2013, 5:33 p.m.

#10

M-1 and LINEQU function pretty much the same underneath. They both perform a Doolittle LU decomposition with partial pivoting and then solve the system of equations (many times for M-1).

I've no idea what is causing your problem :-(

- Pauli

Edited: 5 Jan 2013, 8:03 p.m.

#11

Dieter, have you tried re-flashing the 34s software?


John


#12

Yes, of course a firmware update was the first thing I tried. But the problem showed up with version 3.1 3325 as well as 3.2 3350. It seems to be a hardware problem.

Dieter


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