Search found 39 matches

by whuyse
Fri May 17, 2019 10:16 am
Forum: Discuss!
Topic: Precision of the Exponential Integral on DM42
Replies: 1
Views: 297

Re: Precision of the Exponential Integral on DM42

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 ...
by whuyse
Thu Feb 28, 2019 2:36 pm
Forum: DM42
Topic: Looking forward to the DM42 update utilizing the Free42 2.023 update...
Replies: 29
Views: 2443

Re: Looking forward to the DM42 update utilizing the Free42 2.023 update...

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
by whuyse
Thu Feb 28, 2019 2:11 pm
Forum: DM42
Topic: Looking forward to the DM42 update utilizing the Free42 2.023 update...
Replies: 29
Views: 2443

Re: Looking forward to the DM42 update utilizing the Free42 2.023 update...

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
by whuyse
Thu Feb 28, 2019 11:00 am
Forum: DM42
Topic: Looking forward to the DM42 update utilizing the Free42 2.023 update...
Replies: 29
Views: 2443

Re: Looking forward to the DM42 update utilizing the Free42 2.023 update...

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...
by whuyse
Wed Feb 13, 2019 9:18 am
Forum: DM42
Topic: Looking forward to the DM42 update utilizing the Free42 2.023 update...
Replies: 29
Views: 2443

Re: Looking forward to the DM42 update utilizing the Free42 2.023 update...

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
by whuyse
Sat Feb 02, 2019 10:01 am
Forum: Usage tips, tricks and problem reports
Topic: The Stack (according to Free42 Manual)
Replies: 19
Views: 1399

Re: The Stack (according to Free42 Manual)

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
by whuyse
Wed Jan 30, 2019 12:20 pm
Forum: Usage tips, tricks and problem reports
Topic: newbie and coding help needed
Replies: 6
Views: 777

Re: newbie and coding help needed

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↓ ...
by whuyse
Wed Jan 30, 2019 7:57 am
Forum: Usage tips, tricks and problem reports
Topic: newbie and coding help needed
Replies: 6
Views: 777

Re: newbie and coding help needed

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...
by whuyse
Tue Jan 29, 2019 11:35 am
Forum: Usage tips, tricks and problem reports
Topic: newbie and coding help needed
Replies: 6
Views: 777

Re: newbie and coding help needed

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 ...
by whuyse
Wed Dec 12, 2018 10:42 am
Forum: DM42
Topic: Feature requests
Replies: 33
Views: 3112

Re: Feature requests

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