Re: [Q]: ID analog to FORTRAN "sign" function

["Mark Hadfield" <m.hadfield(at)niwa.cri.nz>]

"Alex Schuster" <alex@pet.mpin-koeln.mpg.de> wrote in message
39E1C067.16F7488E@pet.mpin-koeln.mpg.de">news:39E1C067.16F7488E@pet.mpin-koeln.mpg.de...
> Rostyslav Pavlichenko wrote:
>
> > Does the IDl have something close to Fortran SIGN (DSIGN... so on...)
> > functions
> > ...
> > result = SIGN (a, b)
> >         a  (Input) Must be of type integer or real.
> >
> >         b  Must have the same type and kind parameters as a.
> >
> > Results:
> > =========
> > The result type is the same as a.
> > The value of the result is
> > | a | if b >= zero
> > and -| a | if b < zero.
>>...
> No, but you can easily write it:
>
> function sign, a, b
>   if ( b ge 0 ) then $
>     return, abs( a ) $
>   else $
>     return, -abs( a )
> end

The following is more compact and works when b is an array

    return, abs(a) * (fix(b ge 0) - fix(b lt 0))

---
Mark Hadfield
m.hadfield@niwa.cri.nz  http://katipo.niwa.cri.nz/~hadfield/
National Institute for Water and Atmospheric Research
PO Box 14-901, Wellington, New Zealand

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