Re: [Gm2] Are there standard functions such as FLOAT and TRUNC?

[Fischlin Andreas]

Dear all,

I recommend to use assignment compatibility if you wish to convert  
among reals of different precision. This means:

VAR
        rs: SHORTREAL;
        r: REAL;
        rl: LONGREAL;

  rs := r;    rs := rl;
  r :=  rs;   r := rl;
  rl := rs;  rl := r;

All of above assignment statements should be legal and do the job you  
want. Any other solution trying to convert in the middle of an  
expression would be implementation dependent. For that reason we use  
in our RAMSES (http://www.sysecol.ethz.ch/SimSoftware/RAMSES/) code  
throughout the assignment technique.

Regards,
Andreas



ETH Zurich
Prof. Dr. Andreas Fischlin
Systems Ecology - Institute of Integrative Biology
CHN E 21.1
Universitaetstrasse 16
8092 Zurich
SWITZERLAND

address@hidden
www.sysecol.ethz.ch

+41 44 633-6090 phone
+41 44 633-1136 fax

Make it as simple as possible, but distrust it!
________________________________________________________________________

On 17/Feb/2010, at 21:14 , Carl Glassberg wrote:

> Hello, again.
>
> Are there standard functions such as FLOAT and TRUNC for conversion  
> to/from SHORTREAL/REAL/LONGREAL?
>
> If not, can VAL(LONGREAL, ...) and so forth be used?
>
> I am planning to test SHORTREAL/REAL/LONGREAL.
>
> So far, this is what gm2 versions of Machar yield as machine  
> constants for floating-point:
>
> (Created by converting machar.c to three gm2 versions, one each for
> SHORTREAL, REAL, LONGREAL)
> --------------------------------------------------------------
> (* SHORTREAL = float *)
> ibeta =           2
> it =              24
> irnd =            5
> ngrd =            0
> machep =         -23
> negep =          -24
> iexp =            8
> minexp =         -126
> maxexp =          128
> eps =   0.1192092E-6
> epsneg =   0.5960464E-7
> xmin =  0.1175494E-37
> xmax =  3.4028234E+38
> ---------------------------------------
> (* REAL = double *)
> ibeta =           2
> it =             53
> irnd =            5
> ngrd =            0
> machep =        -52
> negep =         -53
> iexp =           11
> minexp =        -1022
> maxexp =         1024
> eps =   0.222044604925031E-15
> epsneg =   0.111022302462515E-15
> xmin =  0.222507385850720E-307
> xmax =  1.797693134862315E+308
> -----------------------------------------------
> (* LONGREAL = long double *)
> ibeta =         2
> it =            64
> irnd =          5
> ngrd =          0
> machep =       -63
> negep =        -64
> iexp =          15
> minexp =       -16382
> maxexp =        16384
> eps =    0.108420217248550443E-18
> epsneg =    0.542101086242752217E-19
> xmin =  0.336210314311209350E-4931
> xmax =  1.189731495357231764E+4932
> ----------------------------------------------------
>
> Carl
>
>
>
>
>
>
>
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