www.SwissMicros.com

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...

Thomas Okken wrote: ↑

Tue Feb 12, 2019 10:58 am

• More accurate 2x2 matrix operations
• More accurate dot product using FMA

Yes!!! As this is something the real 42S does, as well (albeit not with FMAs)
Cheers, Werner

Perhaps you should read the first post in this thread before replying..
This is about RPN on the DM42, and of course Joe's remarks are also entirely accurate, as usual.
(well, except for Z=9 which should've been T=9

Cheers, Werner

Just for completeness: the GETKEY approach does work, but it doesn't catch EXIT or the new softkeys. This is what I used to try it out, with the up/down arrow keys and S+ for left and XEQ to go right: 00 { 48-Byte Prgm } 01▸LBL "TRY" 02 CLLCD 03 1 04 ENTER 05 "×" 06▸LBL 10 07 AGRAPH 08 GETKEY 09 R↓ ...

AGRAPH and PIXEL accept a complex matrix of coordinates as argument as well. Beware that complex arguments and real arguments have their order reversed. Complex arguments are (X,Y) with X the horizontal coordinate and Y the vertical (your program has X and Y reversed btw) Then, to add a coordinate t...

Unfortunately, it seems that pressing a menu button clears the LCD as well.. so you can: - create the menu grobs yourself and work with GETKEY (don't know if that will work) - save all 'written' pixel coordinates in a matrix and rewrite them each and every loop. - (kindly) ask Swissmicros to change ...

My feature request (also in view of the virtually unlimited program space) is to lift the limit on having only 8 return stack levels.
That is also unlikely to cause any existing program to fail
Local variables would also be nice..

Cheers, Werner