[Proj] Re: Re: Re: Proj4 Bug (rtodms) excuse me mistake in message corrected

cp ch.panel at free.fr
Fri Nov 10 16:01:42 EST 2006

"Gerald I. Evenden" <gerald.evenden at verizon.mail> a écrit dans le message de
news: 200611101150.07261.gerald.evenden at verizon.mail...
> My conclusion, based upon all the material this thread has generated, is
> that
> either Borland has messed with the rounding mode of the FPU or the machine
> used on the original error has a flawed chip.  Even when the problem is
> rewritten to emulate the Borland optimization, the "OK" solution is the
> result.

No !  it's a bug on the compiler when the second operand is a number and so
when optmization is made by this compiler (optimization that noone has tell
to do).
the lines
res1 =  r/60.0
res1 =  r/60
res1 = r/60.0L
are generated the same code and a DOUBLE precision number is loaded which
represent 1/60. I said DOUBLE and not LONG DOUBLE though a fld tbyte ptr is
in the following lines

  static long double t1 = 1.0L;
  static long double t2=60.0L;
  static long double t3;
  static long double t4;
  double r=240.0;
  t3 = t1 / t2;
  t4 = t1 / 60.0L;

this gives t3 different from t4 because in line t4, /60.0L is optimized and
then replaced by 1/60 in double precisiion and loaded as long double
so LSB -> MSB
t3= 89 88 88 88 88 88 88 88 F9 3F
t4= 00 88 88 88 88 88 88 88 F9 3F

this is how works borland compiler. strange!  isn't it ?

> I would suggest that the originator of this problem submit a bug report to
> Borland in an effort to extract their take on the problem.  Please add a
> summary of the results of this email thread.

no! thank you ! :o)

> I do not think there is sufficient evidence to justify modifying the
> original
> source code.  Perhaps a distribution note could be made to warn users of
> the
> Borland compiler of the problem.

of course not ! don't change anything !  I think only it should be kind that
borland compiler's users are worned about this !

> Or perhaps a compile flag testing for Borland compiler which issues a
> self-destruct message.
> -- 
> The whole religious complexion of the modern world is due
> to the absence from Jerusalem of a lunatic asylum.
> -- Havelock Ellis (1859-1939)  British psychologist
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