[libre-riscv-dev] [Bug 208] implement CORDIC in a general way sufficient to do transcendentals

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=208

--- Comment #5 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
ok so would you like to do the next step? which is, yep you guessed it:
IEEE754 FP sin and cos :)

i think... from doing some reading (last year) i have a vague recollection
that you have to be careful with the smaller ranges at one end, thus
only using a 45 degree range (+/-) and subtracting and adding accordingly
in order to compute an intermediary result, followed by adjustment
(add/subtract to/from fractions of pi).

if you naively try to do from 0-90 then at one end (i forget which) because
sin/cos is flat at one end, something to do with the atan2 tables getting
very small, you end up with inaccuracies creeping in and stacking up
rapidly.

-- 
You are receiving this mail because:
You are on the CC list for the bug.