Re: exercise in double number arithmetic

On Sun, 7 Jul 2024 20:52:43 (UTC), mhx wrote:
..

>
FORTH> 131 dup 2/ chs cr ud.
188694833082770476622296176145946360850
( correct cf. WolframAlpha, but 132 66 CHS is incorrect )
>
-marcel

Same results when using ud. instead of d.
200 value M
create coeffs 2 M * 2* cells allot
: coeffs.init
    coeffs 2 M * 2* cells erase
    2 0 do 1. coeffs i M * 2* cells + 2! loop ;
0 value k
0 value n
: coef.calc { n k -- }
     \ to k to n
     coeffs.init
     n 1+ 1 do
       k 1+ 1 do
         coeffs j 1-  2 mod   M  * i 1- + 2* cells + 2@
         coeffs j 1-  2 mod   M  * i    + 2* cells + 2@
         d+
         coeffs j     2 mod   M  * i    + 2* cells + 2!
       loop
     loop
     coeffs n 2 mod   M  * k + 2* cells + 2@ ud.
;
131 65 coef.calc  188694833082770476622296176145946360850  ok (correct)
132 66 coef.calc 37107299244602489781217744860124510244  ok (incorrect)
Ahmed