OpenEuphoria

Re: Math crashes with translated programs (Rob?)

• Posted by r.schr at t-online.de Jun 13, 2002
• 394 views

Andy Serpa wrote:
> 
> > I didn't get 0 with the interpreter! Correctly it reports:
> >
> >  tst.ex:5
> >  math function overflow error
> >  --> see ex.err
> >
> Really?  Maybe it is a processor thing.  Do you have an Intel?

No, it's an AMD K6-2 .

> ...
> So I need a COMPLETE safe_power() function, it seems, that will protect
> me from overflows from any possible atoms (integer or floating point,
> positive or negative) used for base and exponent.  Anyone?
>

I wouldn't use a "save_power()" function. Instead, I would check the two
arguments before calling power(). May be the following function is
useful for this purpose:
 
-------------------------------------------------------- 
constant lim = log(3e+307)  -- needed for chk_pow_args()

function chk_pow_args(atom a, atom b)
--       ------------
    if a > 0.0 then
        if b*log(a) < lim then
            return 1
        end if
    elsif a < 0 and integer(a) then
        if b*log(-a) < lim then
            return 1
        end if
    end if
    return 0
end function

-- test:

    atom a, b

    a = 0.0951
    b = -300.784
    if chk_pow_args(a,b) then
        ? power( a, b)
    else
        puts(1,"power() overflow! Abort.\n")
    end if
-------------------------------------------------------- 

Have a nice day, Rolf