Re: High level FSIN and FCOS

"The Beez'" <hansoft@[EMAIL PROTECTED]
> writes:

> Hi!
>
> Does anyone have some high level source for FSIN and FCOS words?

: fsinn ( x -- {sin x}/x )
  fsqr  1 >f  fswap  1 >f  0 >r  begin ( a x^2 t ; k )
  1 r+!  fover f*  r 2* >f f/  r 2* 1+ >f f/ fnegate ( a x^2 t' ; k' )
  frot  fover fover f+ ( x^2 t' a a' ; k' )
  ftuck f= >r f-rot r> until ( a' x^2 t' ; k' )
  fdrop fdrop  r> drop
;
: fsin  fdup fsinn f* ;

: r+!  rp@[EMAIL PROTECTED]
 +! ;
: >f  s>d d>f ;
: f-rot  frot frot ;

Obviously, it won't work for large arguments, you need another
way to calculate Taylor serie, but you want to take argument modulo pi
anyway.

cos(x) = sin (pi - x)

> BTW, FLN, F** or others are appreciated as well.

x^y = exp(y ln x)

Logarithm is problematic.
Taylor series for ln (1+x) converge for |x| < 1.
The best approach is probably extracting decimal order,
thus reducing to arguments between 1 and 10.


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