Floating-Point Support

Article
07/11/2012

Many Microsoft run-time library functions require floating-point support from a math coprocessor or from the floating-point libraries that accompany the compiler. Floating-point support functions are loaded only if required.

When you use a floating-point type specifier in the format string of a call to a function in the printf or scanf family, you must specify a floating-point value or a pointer to a floating-point value in the argument list to tell the compiler that floating-point support is required.

To handle floating-point exceptions, refer to the sample code in the _fpieee_flt topic.

Floating-point precision of intermediate values are controlled by the functions _control87, _controlfp, __control87_2. By default, _controlfp's precision control is set to 53 bits (_PC_53). Linking with FP10.OBJ changes the default precision control to 64 bits (_PC_64). On the linker command line, FP10.OBJ must appear before LIBC.LIB, LIBCMT.LIB, or MSVCRT.LIB.

Floating-Point Functions

Routine	Use	.NET Framework equivalent
abs	Return absolute value of int	System::Math::Abs
acos, acosf	Calculate arccosine	System::Math::Acos
asin, asinf	Calculate arcsine	System::Math::Asin
atan, atanf, atan2, atan2f	Calculate arctangent	System::Math::Atan, System::Math::Atan2
atof, _atof_l, _wtof, _wtof_l	Convert character string to double-precision floating-point value	System::Convert::ToSingle, System::Convert::ToDouble
Bessel functions	Calculate Bessel functions _j0, _j1, _jn, _y0, _y1, _yn	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
_cabs	Find absolute value of complex number	Not applicable.
ceil, ceilf	Find integer ceiling	System::Math::Ceiling
_chgsign, _chgsignl	Reverse sign of double-precision floating-point or long double-precision floating-point argument	Not applicable.
_clear87, _clearfp	Get and clear floating-point status word	Not applicable.
_control87, _controlfp, __control87_2, _controlfp_s	Get old floating-point control word and set new control-word value	Not applicable.
_copysign, _copysignl	Return one value with sign of another	Not applicable.
cos, cosf, cosh, coshf	Calculate cosine	System::Math::Cos, System::Math::Cosh
difftime	Compute difference between two specified time values	System::DateTime::Subtract
div	Divide one integer by another, returning quotient and remainder	Not applicable.
_ecvt, _ecvt_s	Convert double to character string of specified length	System::Convert::ToString
exp, expf	Calculate exponential function	System::Math::Exp
fabs, fabsf	Find absolute value	System::Math::Abs
_fcvt, _fcvt_s	Convert double to string with specified number of digits following decimal point	System::Convert::ToString
_finite	Determine whether given double-precision floating-point value is finite	System::Double::IsInfinity
floor, floorf	Find largest integer less than or equal to argument	System::Math::Floor
fmod, fmodf	Find floating-point remainder	System::Math::IEEERemainder
_fpclass	Return status word containing information on floating-point class	System::Double::IsInfinity, System::Double::IsNegativeInfinity, System::Double::IsPositiveInfinity, System::Double::IsNan
_fpieee_flt	Invoke user-defined trap handler for IEEE floating-point exceptions	Not applicable.
_fpreset	Reinitialize floating-point math package
frexp	Calculate exponential value	Not applicable.
_gcvt, _gcvt_s	Convert floating-point value to character string	System::Convert::ToString
_hypot, hypotf	Calculate hypotenuse of right triangle	Not applicable.
_isnan	Check given double-precision floating-point value for not a number (NaN)	System::Double::IsNan
labs	Return absolute value of long	System::Math::Abs
ldexp	Calculate product of argument and 2 to specified power	System::Math::Pow
ldiv	Divide one long integer by another, returning quotient and remainder	Not applicable.
log, logf, log10, log10f	Calculate natural or base-10 logarithm.	System::Math::Log, System::Math::Log10
_logb	Extract exponential value of double-precision floating-point argument	Not applicable.
_lrotl, _lrotr	Shift unsigned long int left (_lrotl) or right (_lrotr)	Not applicable.
_matherr	Handle math errors	Not applicable.
__max	Return larger of two values	System::Math::Max
__min	Return smaller of two values	System::Math::Min
modf, modff	Split argument into integer and fractional parts	Not applicable.
_nextafter	Return next representable neighbor	Not applicable.
pow, powf	Calculate value raised to a power	System::Math::Pow
printf, _printf_l, wprintf, _wprintf_l, printf_s, _printf_s_l, wprintf_s, _wprintf_s_l	Write data to stdout according to specified format	System::Console::Write, System::Console::WriteLine
rand, rand_s	Get pseudorandom number	System::Random Class
_rotl, _rotr	Shift unsigned int left (_rotl) or right (_rotr)	Not applicable.
_scalb	Scale argument by power of 2	Not applicable.
scanf, wscanf, scanf_s, _scanf_s_l, wscanf_s, _wscanf_s_l	Read data from stdin according to specified format and write data to specified location	System::Console::Read, System::Console::ReadLine
_set_controlfp	set new control-word value	Not applicable.
sin, sinf, sinh, sinhf	Calculate sine or hyperbolic sine	System::Math::Sin, System::Math::Sinh
sqrt	Find square root	System::Math::Sqrt
srand	Initialize pseudorandom series	System::Random Class
_status87, _statusfp, _statusfp2	Get floating-point status word	Not applicable.
strtod, _strtod_l, wcstod, _wcstod_l	Convert character string to double-precision value	System::Convert::ToDouble
tan, tanf, tanh, tanhf	Calculate tangent or hyperbolic tangent	System::Math::Tan, System::Math::Tanh

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Floating-Point Support

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