Re: Complex square root of -1 : zsqrt(-1)

On Wed, 28 Aug 2024 22:10:46 +0000, ahmed wrote:

On Wed, 28 Aug 2024 21:42:15 +0000, mhx wrote:
>

How about

[..]

Yes, your definition captures my approach (idea).
It works but for 0e 0e xpythag gives 0e and the fstack is not consumed.
>
>
We must empty the fstack in this case.
the defintion becomes
>
: xpythag ( F: a b -- c ) \ compute sqrt(a^2+b^2) without overflow
FABS FSWAP FABS FSWAP
F2DUP F> IF  FOVER ( F: a b a -- ) F/ FSQR F1+ FSQRT  F*  EXIT  ENDIF
FDUP F0= IF  fdrop fdrop 0e
       ELSE  FTUCK ( F: b a b -- ) F/ FSQR F1+ FSQRT  F*
      ENDIF ;
and for z** we can use this defintion of xpythag for |z|

Thanks! This fixes a dormant bug in my XFLOAT-svdcmp...
But I will use "FDUP F0= IF  FDROP " ( stack holds 0e 0e at this point
).
-marcel