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

On Sun, 25 Aug 2024 8:34:02 +0000, ahmed wrote:

Hi,
With gforth, complex.fs included.
>
When calculating the square root of -1, I find that:
-1e 0e 0.5e 0e z** z. 0.0000000000000000612303176911189+1.i  ok
-1e 0e zsqrt z. NaN ok
>
>
What's the problem with zsqrt?

Of course you know that fp operations are nearly always just
approximations.
IOW you could improve gforth's original definition to suit your
needs:
: zsqrt    ( z -- sqrt[z] )
    zdup z0= 0= IF
fdup f0= IF  fdrop fsqrt 0e  EXIT  THEN
zln z2/ zexp  THEN ;