39. Type-generic math `<tgmath.h>`#

The header <tgmath.h> includes the headers <math.h> and <complex.h> and defines several type-generic macros.

Of the <math.h> and <complex.h> functions without an f (float) or l (long double) suffix, several have one or more parameters whose corresponding real type is double. For each such function, except modf, there is a corresponding type-generic macro. [1] The parameters whose corresponding real type is double in the function synopsis are generic parameters. Use of the macro invokes a function whose corresponding real type and type domain are determined by the arguments for the generic parameters. [2]

Use of the macro invokes a function whose generic parameters have the corresponding real type determined as follows:

First, if any argument for generic parameters has type long double, the type determined is long double.
Otherwise, if any argument for generic parameters has type double or is of integer type, the type determined is double.
Otherwise, the type determined is float.

For each unsuffixed function in <math.h> for which there is a function in <complex.h> with the same name except for a c prefix, the corresponding type-generic macro (for both functions) has the same name as the function in <math.h>. The corresponding type-generic macro for fabs and cabs is fabs.

`<math.h>` functions	`<complex.h>` functions	type-generic funcions
acos	cacos	acos
asin	casin	asin
atan	catan	atan
acosh	cacosh	acosh
asinh	casinh	asinh
atanh	catanh	atanh
cos	ccos	cos
sin	csin	sin
tan	ctan	tan
cosh	ccosh	cosh
sinh	csinh	sinh
tanh	ctanh	tanh
exp	cexp	exp
log	clog	log
pow	cpow	pow
sqrt	csqrt	sqrt
fabs	cabs	fabs

If at least one argument for a generic parameter is complex, then use of the macro invokes a complex function; otherwise, use of the macro invokes a real function.

For each unsuffixed function in <math.h> without a c-prefixed counterpart in <complex.h>, the corresponding type-generic macro has the same name as the function. These type-generic macros are:

atan2     fma     llround     remainder

cbrt       fmax    log10       remquo

ceil       fmin    log1p       rint

copysign   fmod    log2        round

erf        frwxp   logb        scalbn

erfc       hypot   lrint       scalbln

exp2       ilogb   lround      tgamma

expm1      ldexp   nearbyint   trunc

fdim       lgamma nextafter

floor      llrint nexttoward

If all arguments for generic parameters are real, then use of the macro invokes a real function; otherwise, use of the macro results in undefined behavior.

For each unsuffixed function in <complex.h> that is not a c-prefixed counterpart to a function in <math.h>, the corresponding type-generic macro has the same name as the function. These type-generic macros are:

carg cimag conj cproj creal

Use of the macro with any real or complex argument invokes a complex function.

EXAMPLE With the declarations

#include <tgmath.h>
int n;
float f;
double d;
long double ld;
float complex fc;
double complex dc;
long double complex ldc;

functions invoked by use of type-generic macros are shown in the following table:

macro use	invokes
`exp(n)`	`exp(n)`, the function
`acosh(f)`	`acoshf(f)`
`sin(d)`	`sin(d)`, the function
`atan(ld)`	`atanl(ld)`
`log(fc)`	`clogf(fc)`
`sqrt(dc)`	`csqrt(dc)`
`pow(ldc, f)`	`cpowl(ldc, f)`
`remainder(n, n)`	`remainder(n, n)`, the function
`nextafter(d, f)`	`nextafter(d, f)`, the function
`nexttoward(f, ld)`	`nexttowardf(f, ld)`
`copysign(n, ld)`	`copysignl(n, ld)`
`ceil(fc)`	`undefined behavior`
`rint(dc)`	`undefined behavior`
`fmax(ldc, ld)`	`undefined behavior`
`carg(n)`	`carg(n)`, the function
`cproj(f)`	`cprojf(f)`
`creal(d)`	`creal(d)`, the function
`cimag(ld)`	`cimagl(ld)`
`fabs(fc)`	`cabsf(fc)`
`carg(dc)`	`carg(dc)`, the function
`cproj(ldc)`	`cprojl(ldc)`

39. Type-generic math <tgmath.h>#

39. Type-generic math `<tgmath.h>`#