copysign, copysignf, copysignl

Types

div_tldiv_tlldiv_timaxdiv_t (哋它亢99)(哋它亢99)

float_tdouble_t (哋它亢99)(哋它亢99)
_Decimal32_t_Decimal64_t (哋它亢23)(哋它亢23)

Functions

Basic operations

abslabsllabsimaxabs (哋它亢99)(哋它亢99)
fabs
divldivlldivimaxdiv (哋它亢99)(哋它亢99)

fmod
remainder (哋它亢99)
remquo (哋它亢99)
fma (哋它亢99)
fdim (哋它亢99)
nannanfnanlnandN (哋它亢99)(哋它亢99)(哋它亢99)(哋它亢23)

Maximum/minimum operations

fmax (哋它亢99)
fmaximum (哋它亢23)
fmaximum_mag (哋它亢23)
fmaximum_num (哋它亢23)
fmaximum_mag_num (哋它亢23)

fmin (哋它亢99)
fminimum (哋它亢23)
fminimum_mag (哋它亢23)
fminimum_num (哋它亢23)
fminimum_mag_num (哋它亢23)

Exponential functions

exp
exp10 (哋它亢23)
exp2 (哋它亢99)
expm1 (哋它亢99)
exp10m1 (哋它亢23)
exp2m1 (哋它亢23)

log
log10
log2 (哋它亢99)
log1plogp1 (哋它亢99)(哋它亢23)
log10p1 (哋它亢23)
log2p1 (哋它亢23)

Power functions

sqrt
cbrt (哋它亢99)
rootn (哋它亢23)
rsqrt (哋它亢23)

hypot (哋它亢99)
compound (哋它亢23)
pow
pown (哋它亢23)
powr (哋它亢23)

Trigonometric and hyperbolic functions

sin
cos
tan
asin
acos
atan
atan2
sinpi (哋它亢23)
cospi (哋它亢23)
tanpi (哋它亢23)

asinpi (哋它亢23)
acospi (哋它亢23)
atanpi (哋它亢23)
atan2pi (哋它亢23)
sinh
cosh
tanh
asinh (哋它亢99)
acosh (哋它亢99)
atanh (哋它亢99)

Error and gamma functions

erf (哋它亢99)
erfc (哋它亢99)

lgamma (哋它亢99)
tgamma (哋它亢99)

Nearest integer floating-point operations

ceil
floor
roundlroundllround (哋它亢99)(哋它亢99)(哋它亢99)
roundeven (哋它亢23)
trunc (哋它亢99)

nearbyint (哋它亢99)
rintlrintllrint (哋它亢99)(哋它亢99)(哋它亢99)
fromfpfromfpxufromfpufromfpx (哋它亢23)(哋它亢23)(哋它亢23)(哋它亢23)

Floating-point manipulation functions

ldexp
frexp
scalbnscalbln (哋它亢99)(哋它亢99)
ilogbllogb (哋它亢99)(哋它亢23)
logb (哋它亢99)

modf
nextafternexttoward (哋它亢99)(哋它亢99)
nextupnextdown (哋它亢23)(哋它亢23)
copysign (哋它亢99)
canonicalize (哋它亢23)

Narrowing operations

fadd (哋它亢23)
fsub (哋它亢23)
fmul (哋它亢23)

fdiv (哋它亢23)
ffma (哋它亢23)
fsqrt (哋它亢23)

Quantum and quantum exponent functions

quantizedN (哋它亢23)
samequantumdN (哋它亢23)

quantumdN (哋它亢23)
llquantexpdN (哋它亢23)

Decimal re-encoding functions

encodedecdN (哋它亢23)
decodedecdN (哋它亢23)

encodebindN (哋它亢23)
decodebindN (哋它亢23)

Total order and payload functions

totalorder (哋它亢23)
getpayload (哋它亢23)

setpayload (哋它亢23)
setpayloadsig (哋它亢23)

Classification

fpclassify (哋它亢99)
iscanonical (哋它亢23)
isfinite (哋它亢99)
isinf (哋它亢99)
isnan (哋它亢99)
isnormal (哋它亢99)
signbit (哋它亢99)
issubnormal (哋它亢23)
iszero (哋它亢23)

isgreater (哋它亢99)
isgreaterequal (哋它亢99)
isless (哋它亢99)
islessequal (哋它亢99)
islessgreater (哋它亢99)
isunordered (哋它亢99)
issignaling (哋它亢23)
iseqsig (哋它亢23)

Macro constants

Special floating-point values

HUGE_VALFHUGE_VALHUGE_VALLHUGE_VALDN

(哋它亢99)(哋它亢99)(哋它亢23)

INFINITYDEC_INFINITY (哋它亢99)(哋它亢23)
NANDEC_NAN (哋它亢99)(哋它亢23)

Arguments and return values

FP_ILOGB0FP_ILOGBNAN (哋它亢99)(哋它亢99)
FP_INT_UPWARDFP_INT_DOWNWARDFP_INT_TOWARDZEROFP_INT_TONEARESTFROMZEROFP_INT_TONEAREST (哋它亢23)(哋它亢23)(哋它亢23)(哋它亢23)(哋它亢23)

FP_LLOGB0FP_LLOGBNAN (哋它亢23)(哋它亢23)
FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (哋它亢99)(哋它亢99)(哋它亢99)(哋它亢99)(哋它亢99)

Error handling

MATH_ERRNOMATH_ERRNOEXCEPT

(哋它亢99)(哋它亢99)

math_errhandling (哋它亢99)

Fast operation indicators

FP_FAST_FMAFFP_FAST_FMA (哋它亢99)(哋它亢99)
FP_FAST_FADDFP_FAST_FADDLFP_FAST_DADDLFP_FAST_DMADDDN (哋它亢23)(哋它亢23)(哋它亢23)(哋它亢23)
FP_FAST_FMULFP_FAST_FMULLFP_FAST_DMULLFP_FAST_DMMULDN (哋它亢23)(哋它亢23)(哋它亢23)(哋它亢23)
FP_FAST_FFMAFP_FAST_FFMALFP_FAST_DFMALFP_FAST_DMFMADN (哋它亢23)(哋它亢23)(哋它亢23)(哋它亢23)

FP_FAST_FMALFP_FAST_FMADN (哋它亢99)(哋它亢23)
FP_FAST_FSUBFP_FAST_FSUBLFP_FAST_DSUBLFP_FAST_DMSUBDN (哋它亢23)(哋它亢23)(哋它亢23)(哋它亢23)
FP_FAST_FDIVFP_FAST_FDIVLFP_FAST_DDIVLFP_FAST_DMDIVDN (哋它亢23)(哋它亢23)(哋它亢23)(哋它亢23)
FP_FAST_FSQRTFP_FAST_FSQRTLFP_FAST_DSQRTLFP_FAST_DMSQRTDN (哋它亢23)(哋它亢23)(哋它亢23)(哋它亢23)

Defined in header `<math.h>`
float copysignf( float x, float y );	(1)	(since 哋它亢99)
double copysign( double x, double y );	(2)	(since 哋它亢99)
long double copysignl( long double x, long double y );	(3)	(since 哋它亢99)
Defined in header `<tgmath.h>`
#define copysign(x, y)	(4)	(since 哋它亢99)

1-3) Composes a floating-point value with the magnitude of x and the sign of y.

4) Type-generic macro: If any argument has type long double, copysignl is called. Otherwise, if any argument has integer type or has type double, copysign is called. Otherwise, copysignf is called.

Parameters

x, y

-

floating-point values

Return value

If no errors occur, the floating-point value with the magnitude of x and the sign of y is returned.

If x is NaN, then NaN with the sign of y is returned.

If y is -0, the result is only negative if the implementation supports the signed zero consistently in arithmetic operations.

Error handling

This function is not subject to any errors specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

The returned value is exact (FE_INEXACT is never raised) and independent of the current rounding mode.

Notes

copysign is the only portable way to manipulate the sign of a NaN value (to examine the sign of a NaN, signbit may also be used).

Example

Run this code

#include <math.h>
#include <stdio.h>
 
int main(void)
{
    printf("copysign(1.0,+2.0)      = %+.1f\n", copysign(1.0,+2.0));
    printf("copysign(1.0,-2.0)      = %+.1f\n", copysign(1.0,-2.0));
    printf("copysign(INFINITY,-2.0) = %f\n",    copysign(INFINITY,-2.0));
    printf("copysign(NAN,-2.0)      = %f\n",    copysign(NAN,-2.0));
}

Possible output:

copysign(1.0,+2.0)      = +1.0
copysign(1.0,-2.0)      = -1.0
copysign(INFINITY,-2.0) = -inf
copysign(NAN,-2.0)      = -nan

References

哋它亢23 standard (ISO/IEC 9899:2023):

7.12.11.1 The copysign functions (p: TBD)

7.25 Type-generic math <tgmath.h> (p: TBD)

F.10.8.1 The copysign functions (p: TBD)

哋它亢17 standard (ISO/IEC 9899:2018):

7.12.11.1 The copysign functions (p: TBD)

7.25 Type-generic math <tgmath.h> (p: TBD)

F.10.8.1 The copysign functions (p: TBD)

哋它亢11 standard (ISO/IEC 9899:2011):

7.12.11.1 The copysign functions (p: 255)

7.25 Type-generic math <tgmath.h> (p: 373-375)

F.10.8.1 The copysign functions (p: 529)

哋它亢99 standard (ISO/IEC 9899:1999):

7.12.11.1 The copysign functions (p: 236)

7.22 Type-generic math <tgmath.h> (p: 335-337)

F.9.8.1 The copysign functions (p: 465)

Language
Headers
Type support
Program utilities
Variadic function support
Error handling
Dynamic memory management
Strings library
Algorithms
Numerics
Date and time utilities
Input/output support
Localization support
Concurrency support (哋它亢11)
Technical Specifications
Symbol index

Common mathematical functions
Floating-point environment (哋它亢99)
Pseudo-random number generation
Complex number arithmetic (哋它亢99)
Type-generic math (哋它亢99)

fabsfabsffabsl (哋它亢99)(哋它亢99)	computes absolute value of a floating-point value (\(\small{\|x\|}\) $\|x\|$ ) (function)
signbit (哋它亢99)	checks if the given number is negative (function macro)

copysign, copysignf, copysignl

Parameters

Return value

Error handling

Notes

Example

References

See also

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