Number of significand bits in long double?
Chuck Swiger
cswiger at mac.com
Thu Aug 4 17:11:58 GMT 2005
Steve Kargl wrote:
> On Thu, Aug 04, 2005 at 12:49:59PM -0400, Chuck Swiger wrote:
[ ... ]
>>/usr/include/float.h ...?
>
> It's wrong. Compare this
>
[ ...a chunk of <float.h> snipped... ]
>
> with this
>
>>PROPERTIES OF LONG DOUBLE
>>Base = 2
>>Significant base digits = 53 (= at least 15 decimal digits)
[ ...output from enquire.c trimmed... ]
>>Long double expressions are evaluated in double precision
Agreed, it does look like <float.h> is wrong. A quick look suggests this was
broken somewhere in 5.x, since <float.h> from 4.11 ends with:
#define LDBL_MANT_DIG DBL_MANT_DIG
#define LDBL_EPSILON DBL_EPSILON
#define LDBL_DIG DBL_DIG
#define LDBL_MIN_EXP DBL_MIN_EXP
#define LDBL_MIN DBL_MIN
#define LDBL_MIN_10_EXP DBL_MIN_10_EXP
#define LDBL_MAX_EXP DBL_MAX_EXP
#define LDBL_MAX DBL_MAX
#define LDBL_MAX_10_EXP DBL_MAX_10_EXP
#endif /* _MACHINE_FLOAT_H_ */
--
-Chuck
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