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digitalmars.D.bugs - [Issue 356] New: std,math.tan doesn't preserve NaN payloads [fix included]

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=356

           Summary: std,math.tan doesn't preserve NaN payloads [fix
                    included]
           Product: D
           Version: 0.167
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: minor
          Priority: P1
         Component: Phobos
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: clugdbug yahoo.com.au


Currently in tan(x), it effectively does 
  if (isnan(x)) return real.nan; 
when it should be
  if (isnan(x)) return x;

The good news is that all math functions preserve NaN payloads, with this one
exception. And it's a one-line fix.
In the asm code for tan, at the end of the code, add the line "jnp Lret".

-------
trigerr:
    jnp Lret            ; // if x is NaN, return x.   <<< ADD THIS LINE
    fstp    ST(0)       ; // dump x, which will be infinity
    }
    return real.nan;

Lret:
    ;
}
---------

Also, tan() currently fails one if its unit tests ( tan(1e100)). Since the
isnan(tan(1e100)) is not correct mathematically, I think that line should just
be removed.
--------
            // overflow
            [   real.infinity,  real.nan],
            [   real.nan,       real.nan],
            [   1e+100,         real.nan], <<< REMOVE THIS LINE
    ];
--------


-- 
Sep 20 2006
next sibling parent Don Clugston <dac nospam.com.au> writes:
d-bugmail puremagic.com wrote:
 http://d.puremagic.com/issues/show_bug.cgi?id=356
 
            Summary: std,math.tan doesn't preserve NaN payloads [fix
                     included]
            Product: D
            Version: 0.167
           Platform: PC
         OS/Version: Windows
             Status: NEW
           Severity: minor
           Priority: P1
          Component: Phobos
         AssignedTo: bugzilla digitalmars.com
         ReportedBy: clugdbug yahoo.com.au
 
 
 Currently in tan(x), it effectively does 
   if (isnan(x)) return real.nan; 
 when it should be
   if (isnan(x)) return x;
 
 The good news is that all math functions preserve NaN payloads, with this one
 exception. And it's a one-line fix.

I spoke too soon. The version(linux) form of pow() should have two lines changed: if (isnan(y)) return y; // <<< instead of "return real.nan" <<<<<<<< if (y == 0) return 1; // even if x is $(NAN) if (isnan(x) && y != 0) return x; // instead of "return real.nan;" <<<<<<
Sep 25 2006
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=356


bugzilla digitalmars.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED




------- Comment #2 from bugzilla digitalmars.com  2006-10-04 20:00 -------
Fixed DMD 0.168


-- 
Oct 04 2006