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Matrix Viewer and rudimentary editor This is a first try, and there are tons of things I will be changing still, but it works quite well as it is. Try it out with the included test matrices M44 and C24x5. before you start MVIEW is packaged with all its subroutines, the digit font matrix DF and a few...

I assign the LO routine to shift R/S and use this to turn off the calculator.

Are you sure you're talking about the DM42..?

Cheers, Werner

GETKEY behaves erratically on the first row of keys (not the menu keys).
The real DM42 returns 1-6 for the row S+ to XEQ, and doesn't work for the menu keys (which is a pity, BTW)
The DM42 skin returns 1-6 for the menu keys and 2192 for S+, 2072 for 1/X etc.

Cheers, Werner

in Free42 (and the DM42) you can store up to 14 characters per register instead of only 6, using the following utilities to transform up to 14 characters to the X register (A2X) and its inverse (X2A) 00 { 77-Byte Prgm } 01>LBL "A2X" 02 ALENG 03 14 04 X>Y? 05 X<>Y 06 25600 07 0 08>LBL 03 09 % 10 ATOX...

It’s a printout from the Dm42 itself, not compatible with the program import. To import, use the .raw file.
Cheers, Werner

0. Abstract My ultimate goal is to draw a chess board. To achieve this in a modular fashion, we'll need tools to draw lines horizontally and vertically, use these to draw a grid, and then be able to fill half of the grid cells with a shading pattern. So, without further ado: 1. HLINE X Y Z T In: n ...

Show us your code, please? And that site will simply use N+k-digit arithmetic and constants to get to the precision requested (N) ie. they'll use gamma to N+k digits to guarantee the result is accurate to N digits. eg. for x=-30 the largest summation term is about 2.7e10 so an extra 10 or 11 digits ...

in my second-to-last post, 'extended precision' was but an example - that's why I said 'i.a.' - it's the resulting accuracy that counts.
And yes, all of that applies to the complex case as well. A DOT product of 2 complex vectors is obtained using 4 real dot products.
Cheers, Werner

We spoke of this before, can't remember whether it was here or at the hpmuseum.
There is a way to use FMAs to implement dot products, and obtain a result that is as accurate as if you used double precision.
I'll see if I can find it again,
Werner

Werner, do you know exactly which functions in the HP-42S use special-case logic for 2x2 matrices? I know DET does - it simply evaluates ab-cd in 15-digit precision. The others, I'll perform some tests. And what about higher-precision dot products? Obviously DOT, but matrix-matrix multiplication is...