## DM15L_M1B and Matrix limits

Forum for discussion of the DM10, DM11, DM12, DM15, DM16 and DM41 units
Boub65
Posts: 174
Joined: Tue Sep 12, 2017 4:34 pm
Location: Rabat, Morocco

### DM15L_M1B and Matrix limits

Hi all,
I've read somewhere that we were limited to 64 Matrix elements total, even if we used more than one Matrix.

I did try to fill manually (USER Mode) two matrices :
A = 3x16 = 48 elements
B = 2x16 = 32 elements
with success... although 46 + 32 = 80 > 64 elements!

So here are my questions :
1) did the "64 limit" change with (some) new firmware?
2) if not... what are the Matrices operations/instructions that will fail, because standard fill and retrieve Matrix 1, STO A (or B) and/or RCL A (or B) for each element works!
3) if I only use my two Matrices to store and retrieve data (with no specific Matrices operations) am I ok?
Sincèrement, Sincerely, 73,
Boubker

2xDM15L, DM41L, DM42 SN#00855 (+one lost during shipping), DM41X #00707
TI-89 titanium, CASIO fx-cg50 (to play with micropython)

There are three kinds of people in the world: those who know math and those who don't.
rawi
Posts: 40
Joined: Sat Dec 28, 2019 4:50 am
Location: Bavaria, Germany

### Re: DM15L_M1B and Matrix limits

Hi Boub65,

you are right: The manual for the HP 15 C states, that there can be a total of 64 matrix elements, that can be used for 1 matrix or distributed to up to 5 matrices.

On Swiss micros webiste (found here: https://www.swissmicros.com/product/dm15l ) there is only the limitation that the maximum size of matrices for solving linear equations or computung the inverse is limited to 8*8. I put in a 8*8-matrix A and a 8*1-matrix b and solved the linear equation A*x=b storing the result in c. So in total I had 80 matrix elements and it worked fine.

Furthermore I copied a 8*8-matrix A to a 8*8-matrix B and it worked with 128 storage places used. I still could get the determinant of B but not get the inverse because of memory limitations. So an intersting question is, where the limit is. It is definitely significantly more extended than with the original HP 15 C but I do not know what the exact limit is.

Best

Raimund