Type-generic math

For ISO C Standard 11 (C11) and later, the <tgmath.h> header, in addition to including <math.h> and <complex.h>, provides macros that invoke a corresponding math function based on the types of the parameters.

C runtime library math functions come in real and complex variants. Each variant comes in three flavors, depending on the type of the argument: float, double, and long double. Because C doesn't support overloading like C++ does, each variant has a different name. For example, to get the absolute value of a real floating-point value, you'd call either fabsf, fabs, or fabsl depending on whether you're passing a float, double, or long double value, respectively. To get the complex absolute value, you'd call one of cabsf, cabs, or cabsl depending on whether you're passing a float, double, and long double complex value, respectively. If the arguments don't match any of the above mentioned types, the function is chosen as though the arguments were doubles.

<tgmath.h> contains macros that simplify the selection of the right math function to call. The macros examine the type they're passed and then call the right function. For example, the sqrt macro binds sqrt(9.9f) to sqrtf(), but it binds sqrt(9.9) to sqrt(). If at least one macro argument for a generic parameter is complex, then the macro binds to a complex function; otherwise, it invokes a real function.

The type-generic macros in <tgmath.h> allow you to write more portable code because you don't need to manage casting or selecting different function names depending on the type of argument.

These macros are in their own header so that programs written using the <math.h> header won't break. So double x = sin(42); behaves as it always has when you include <math.h>. Even so, most existing C programs are expected to be unaffected when the <tgmath.h> header is included instead of <math.h> or <complex.h>.

The following table lists the macros that are available in <tgmath.h> and what they expand to. modf isn't included in this table because it doesn't have a corresponding type-generic macro because it isn't clear how to make it safe without complicating type resolution.

Macro Real
long double
long double
acos acosf acos acosl cacosf cacos cacosl
acosh acoshf acosh acoshl cacoshf cacosh cacoshl
asin asinf asin asinl casinf casin casinl
asinh asinhf asinh asinhl casinhf casinh casinhl
atan atanf atan atanl catanf catan catanl
atanh atanhf atanh atanhl catanhf catanh catanhl
cos cosf cos cosl ccosf ccos ccosl
cosh coshf cosh coshl ccoshf ccosh ccoshl
exp expf exp expl cexpf cexp cexpl
fabs fabsf fabs fabsl cabsf cabs cabsl
log logf log logl clogf clog clogl
pow powf pow powl cpowf cpow cpowl
sin sinf sin sinl csinf csin csinl
sinh sinhf sinh sinhl csinhf csinh csinhl
sqrt sqrtf sqrt sqrtl csqrtf csqrt csqrtl
tan tanf tan tanl ctanf ctan ctanl
tanh tanhf tanh tanhl ctanhf ctanh ctanhl
atan2 atan2f atan2 atan2l - - -
cbrt cbrtf cbrt cbrtl - - -
ceil ceilf ceil ceill - - -
copysign copysignf copysign copysignl - - -
erf erff erf erfl - - -
erfc erfcf erfc erfcl - - -
exp2 exp2f exp2 exp2l - - -
expm1 expm1f expm1 expm1l - - -
fdim fdimf fdim fdiml - - -
floor floorf floor floorl - - -
fma fmaf fma fmal - - -
fmax fmaxf fmax fmaxl - - -
fmin fminf fmin fminl - - -
fmod fmodf fmod fmodl - - -
frexp frexpf frexp frexpl - - -
hypot hypotf hypot hypotl - - -
ilogb ilogbf ilogb ilogbl - - -
ldexp ldexpf ldexp ldexpl - - -
lgamma lgammaf lgamma lgammal - - -
llrint llrintf llrint llrintl - - -
llround llroundf llround llroundl - - -
log10 log10f log10 log10l - - -
log1p log1pf log1p log1pl - - -
log2 log2f log2 log2l - - -
logb logbf logb logbl - - -
lrint lrintf lrint lrintl - - -
lround lroundf lround lroundl - - -
nearbyint nearbyintf nearbyint nearbyintl - - -
nextafter nextafterf nextafter nextafterl - - -
nexttoward nexttowardf nexttoward nexttowardl - - -
remainder remainderf remainder remainderl - - -
remquo remquof remquo remquol - - -
rint rintf rint rintl - - -
round roundf round roundl - - -
scalbln scalblnf scalbln scalblnl - - -
scalbn scalbnf scalbn scalbnl - - -
tgamma tgammaf tgamma tgammal - - -
trunc truncf trunc truncl - - -
carg - - - cargf carg cargl
conj - - - conjf conj conjl
creal - - - crealf creal creall
cimag - - - cimagf cimag cimagl
cproj - - - cprojf cproj cprojl


Compile with /std:c11.

Windows SDK 10.0.20348.0 (version 2104) or later. See Windows SDK to download the latest SDK. For instructions to install and use the SDK for C11 and C17 development, see Install C11 and C17 support in Visual Studio.

See also

C Run-Time library reference