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Floating-Point Support

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.

Floating-point precision of intermediate values is controlled by the _controlfp. 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
abs Return absolute value of int
acos, acosf Calculate arccosine
asin, asinf Calculate arcsine
atan, atanf, atan2, atan2f Calculate arctangent
atof Convert character string to double-precision floating-point value
Bessel functions Calculate Bessel functions _j0, _j1, _jn, _y0, _y1, _yn
_cabs Find absolute value of complex number
ceil, ceilf Find integer ceiling
_chgsign Reverse sign of double-precision floating-point argument
_clear87, _clearfp Get and clear floating-point status word
_control87, _controlfp Get old floating-point control word and set new control-word value
_copysign Return one value with sign of another
cos, cosf, cosh, coshf Calculate cosine
difftime Compute difference between two specified time values
div Divide one integer by another, returning quotient and remainder
_ecvt Convert double to character string of specified length
exp, expf Calculate exponential function
fabs, fabsf Find absolute value
_fcvt Convert double to string with specified number of digits following decimal point
_finite Determine whether given double-precision floating-point value is finite
floor, floorf Find largest integer less than or equal to argument
fmod, fmodf Find floating-point remainder
_fpclass Return status word containing information on floating-point class
_fpieee_flt Invoke user-defined trap handler for IEEE floating-point exceptions
_fpreset Reinitialize floating-point math package
frexp Calculate exponential value
_gcvt Convert floating-point value to character string
_hypot, hypotf Calculate hypotenuse of right triangle
_isnan Check given double-precision floating-point value for not a number (NaN)
labs Return absolute value of long
ldexp Calculate product of argument and 2 to specified power
ldiv Divide one long integer by another, returning quotient and remainder
log, logf, log10, log10f Calculate natural or base-10 logarithm.
_logb Extract exponential value of double-precision floating-point argument
_lrotl, _lrotr Shift unsigned long int left (_lrotl) or right (_lrotr)
_matherr Handle math errors
__max Return larger of two values
__min Return smaller of two values
modf, modff Split argument into integer and fractional parts
_nextafter Return next representable neighbor
pow, powf Calculate value raised to a power
printf, wprintf Write data to stdout according to specified format
rand Get pseudorandom number
_rotl, _rotr Shift unsigned int left (_rotl) or right (_rotr)
_scalb Scale argument by power of 2
scanf, wscanf Read data from stdin according to specified format and write data to specified location
sin, sinf, sinh, sinhf Calculate sine or hyperbolic sine
sqrt Find square root
srand Initialize pseudorandom series
_status87, _statusfp Get floating-point status word
strtod Convert character string to double-precision value
tan, tanf, tanh, tanhf Calculate tangent or hyperbolic tangent

See Also

Run-Time Routines by Category | Run-Time Routines and .NET Framework Equivalents

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