NEW: HP 15C Collectors Edition

[adamj]

Hi all

I haven't posted on here before, but my searches haven't turned up anything so I wondered if forum members could help check this out for me.

I've got a new HP15C CE (Christmas gift!) and it's looking very nice. Nicely produced/presented manual too. A little bit of key bounce sometimes as some people have mentioned, but I do like the feel and my technique I think is improving.

So, my question relates to matrix processing. I ran through the example at the top of Section 12 (pp 138-139) to solve simultaneous equations. This generated the correct result into matrix C, but I found that the last 2 elements of my input matrix A were clobbered.

The input matrices are set up as follows:

Code:


A
  3.8      7.2
  1.3     -0.9

B
 16.5
-22.1

At the end of the example, the state of the three matrices was as follows:

Code:


A
  3.8      7.2
  0.3421  -3.3632  <---- these elements changed

B
 16.5
-22.1

C
-11.2887
  8.2496

For people who don't have the manual to hand, the calculation is C = inverse A x B (or B/A).
Obviously, I've run through this a number of times and it's repeatable on my unit. On an emulator on my phone, the input matrix A is not changed by the calculation. So while it is certainly possible that this is user error on my part (I need to reset or something), it doesn't feel like correct behaviour.

For reference, running the self test checksum test (2), returns:
ChE--9090h
2023-01-05
C 2008 hP

Serial number: 02870.
Could someone else check this on their calculator?