Name 

Description 

CW_DEFAULT #define 

Header File
float.h
Description
Default control word for 80x87 math coprocessor. 

_chgsign, _chgsignl 

Header File
float.h
Category
Math Routintes
Prototype
double _chgsign(double d);
long double _chgsignl(long double ld);
Description
Reverses the sign of a double-precision floating-point argument, d.
_chgsignl is the long double version; it takes a long double argument and returns a long double result.
Return Value
Returns a value of the same magnitude and exponent as the argument, but with the opposite sign. There is no error return value.
Portability  

_clear87, _clearfp 

Header File
float.h
Category
Math Routines
Prototype
unsigned int _clear87 (void);
unsigned int _clearfp (void);
Description
Clears the floating-point status word.
_clear87 clears the floating-point status word, which is a combination of the 80x87 status word and other conditions detected by the 80x87 exception handler.
_clearfp is identical to _clear87 and is for Microsoft compatibility.
Return Value
The bits in the value returned indicate the floating-point status before it was cleared. For information on the status word, refer to the constants defined in float.h.
Example  

_control87, _controlfp 

Header File
float.h
Category
Math Routines
Prototype
unsigned int _control87(unsigned int newcw, unsigned int mask);
unsigned int _controlfp(unsigned int newcw, unsigned int mask);
Description
Manipulates the floating-point control word.
_control87 retrieves or changes the floating-point control word.
The floating-point control word is an unsigned int that, bit by bit, specifies certain modes in the floating-point package; namely, the precision, infinity, and rounding modes. Changing these modes lets you mask or unmask floating-point exceptions.
_control87 matches the bits in mask to the bits in newcw. If a mask bit equals 1, the corresponding bit in newcw contains the new value for... more 

_copysign, _copysignl 

Header File
float.h
Category
Math Routines
Prototype
double _copysign(double da, double db);
long double _copysignl(long double lda, long double ldb);
Description
Returns the double-precision floating point argument da, with the same sign as the double-precision floating-point argument db.
_copysignl is the long double version; it takes a long double argument and returns a long double result.
Return Value
Returns the first value with the same magnitude and exponent, but with the sign of the second value. There is no error value returned.
Portability  

_finite, _finitel 

Header File
float.h
Category
Math Routines
Prototype
int _finite(double d);
int _finitel(long double ld);
Description
Determines whether a given double-precision floating point value d is finite.
_finitel is the long double version; it takes a long double argument.
Return Value
Returns non-zero if the argument is finite, and 0 if it is not.
Portability  

_fpclass, _fpclassl 

Header File
float.h
Category
Math Routines
Prototype
int _fpclass(double d);
int _fpclassl(long double ld);
Description
Returns an integer value representing the type (class) of an IEEE real for doubles. This value contains information on the floating-point class of the argument.
_fpclassl is the long double version; it takes a long double argument and returns the type (class) of an IEEE real for long doubles.
Return Value
Returns an integer value that indicates the floating-point class of its argument. The possible values, which are listed in the table below, are defined in FLOAT.H.
Portability  

_fpreset 

Header File
float.h
Category
Math Routines
Prototype
void _fpreset(void);
Description
Reinitializes floating-point math package.
_fpreset reinitializes the floating-point math package. This function is usually used in conjunction with system or the exec... or spawn... functions. It is also used to recover from floating-point errors before calling longjmp.

• If you use an 80x87 take the following precautions:
• Do not call system or an exec... or spawn... function while a floating-point... more 

_isnan, _isnanl 

Header File
float.h
Category
Classification Routines, Math Routines
Prototype
int _isnan(double d);
int _isnanl(long double ld);
Description
Tests whether a given double-precision floating-point value d is a NaN.
_isnanl is the long double version; it takes a long double argument.
Return Value
Returns a nonzero value (TRUE) if the value passed in is a NaN; otherwise it returns 0 (FALSE). The non-zero return value corresponds to either _FPCLASS_SNAN, if the NaN is of the signaling type, or _FPCLASS_QNAN, if the NaN is of the quiet type. The values for _FPCLASS_SNAN and _FPCLASS_QNAN are in float.h.
Portability  

_logb, _logbl 

Header File
float.h
Category
Math Routines
Prototype
double _logb(double d);
long double _logbl(long double ld);
Description
Extracts the exponential value of a double-precision floating-point argument. If the argument is denormalized, it is treated as if it were normalized.
_logbl is the long double version; it takes a long double argument and returns a long double result.
Return Value
Returns the unbiased exponent of the value passed in.
Portability  

_nextafter, _nextafterl 

Header File
float.h
Category
Math Routines
Prototype
double _nextafter(double da, double db);
long double _nextafterl(long double lda, long double ldb);
Description
Takes two doubles (da and db) and returns the closest representable neighbor of da in the direction toward db.
If da == db, _nextafter returns da, with no exception triggered. If either da or db is a quiet NaN, then the return value is one or the other of the input NaNs.
_nextafterl is the long double version; it takes a long double argument and returns a long double result.
Return Value
Returns the closest representable neighbor of the... more 

_scalb, _scalbl 

Header File
float.h
Category
Math Routines
Prototype
double _scalb(double d, long exp);
long double _scalbl(long double ld, long exp);
Description
Scales the argument d by a power of 2.
_scalbl is the long double version; it takes a long double argument and returns a long double result.
Return Value
Returns an exponential value if successful. On overflow (depending on the sign of the argument), the function returns +/– HUGE_VAL; the ERRNO variable is set to ERANGE.
Portability  

_status87, _statusfp 

Header File
float.h
Category
Math Routines
Prototype
unsigned int _status87(void);
unsigned int _statusfp(void);
Description
Gets floating-point status.
_status87 gets the floating-point status word, which is a combination of the 80x87 status word and other conditions detected by the 80x87 exception handler.
_statusfp is identical to _status87 and is for Microsoft compatibility.
Return Value
The bits in the return value give the floating-point status. See float.h for a complete definition of the bits returned by _status87 and _status87.
Portability