🚀 go-pugleaf

In article <9212171724.AA01436@fits.cv.nrao.edu>, Lucio Chiappetti <lucio@ifctr.mi.cnr.it> writes...

	(stuff deleted)

>  The conversion from G_FLOAT would be analogous to the R*4 one, but the
>  one for D_FLOAT (the reverse of the ieeed routine in the IRAF VMS assembler
>  routine) is not obviously done in Fortran.
>  What I am uncertain of, is whether I should continue using D_FLOAT on Vax
>  or move to G_FLOAT.
> 
>  I actually use quite a limited amount of REAL*8 values, and I was always
>  happy with applying some scale factors when exceeding the exponent range
>  (1.OE38 for both R*4 and D_FLOAT R*8). From the quoted assembler routine
>  I derive that IRAF does the same.
> 
>  I would appreciate to know other people's opinion on the matter
>  whether G_FLOAT should be recommended on VMS for IEEE compatibility,
>  or not.

I believe that G_FLOAT and H_FLOAT (REAL*16) are not supported on the new Alpha
machines.

We use IDL, which doesn't give the user the option of selecting D_FLOAT or
G_FLOAT (and doesn't support quadruple-precision).  On the VAX, it uses D_FLOAT
numbers for double precision.  (As an aside, IDL does provide built-in support
for converting between IEEE and host formats, for all datatypes it supports.)

Bill Thompson