Math library (libm)

The math library, libm, contains the mathematics functions supplied by the C compilation system. These are described on the Section S manual pages. Here we describe some of the major functions. Note that functions whose names end with the letter f are single-precision versions, which means that their argument and return types are float. Functions whose names end with the letter l are long double-precision versions, which means that their argument and return types are long double. The header file math.h should be included in programs that use math functions.

Math functions

bessel(S)	j0	j1	jn	Bessel functions
	y0	y1	yn	Bessel functions
erf(S)	erfc	erfcf	erfcl	return complementary error function of x
	erf	erff	erfl	return error function of x
exp(S)	cbrt	cbrtf	cbrtl	cube root function
	exp	expf	expl	exponential, mod, power, square root functions
	exp2	exp2f	exp2l	exponential function
	expm1	expm1f	expm1l	exponential function
	frexp	frexpf	frexpl	exponential function
	ldexp	ldexpf	ldexpl	exponential function
	modf	modff	modfl	modulus function
	pow	powf	powl	power function
	pown	pownf	pownl	power function
	scalbln	scalblnf	scalblnl	scalbln function
	scalbn	scalbnf	scalbnl	scalbn function
	sqrt	sqrtf	sqrtl	square root function
fdim(S)	fdim	fdimf	fdiml	return positive difference between two arguments
floor(S)	ceil	ceilf	ceill	return smallest integer not smaller than x
	copysign	copysignf	copysignl	return x with the sign of y
	fabs	fabsf	fabsl	return the absolute value of x, |x|
	floor	floorf	floorl	return largest integer not greater than x
	fmod	fmodf	fmodl	return the floating point remainder of the division of x by y
	nan	nanf	nanl	return a quiet NaN, if available, with content indicated by tagp
	nearbyint	nearbyintf	nearbyintl	return nearest integer value to floating point argument x
	nextafter	nextafterf	nextafterl	return the next representable value in the specified format after x in the direction of y
	nexttoward	nexttowardf	nexttowardl	return the next representable value in the specified format after x in the direction of y
fma(S)	fma	fmaf	fmal	return rounded result of (x x y) + z
fmax(S)	fmax	fmaxf	fmaxl	return maximum numeric value of two arguments
	fmin	fminf	fminl	return minimum numeric value of two arguments
fpclassify(S)	isfinite			determines whether x has a finite value
	isgreater			determines whether x is greater than y
	isgreaterequal			determines whether x is greater than or equal to y
	isinf			determines whether x is positive or negative infinity
	isles			determines whether x is less than y
	islessequal			determines whether x is less than or equal to y
	islessgreater			determines whether x is less than or greater than y
	isnan			determines whether x is a NaN
	isnormal			determines whether x is not zero, subnormal, infinite, or a NaN
	isunordered			determines whether x and y are unordered
	signbit			determines whether the sign of x is negative
gamma(S)	gamma	gammaf	gammal	log gamma function
	lgamma	lgammaf	lgammal	log gamma function
	signgam			storage for sign for gamma and lgamma
	tgamma	tgammaf	tgammal	gamma function
hypot(S)	hypot	hypotf	hypotl	return result of sqrt((x x x) + (y x y))
log(S)	ilogb	ilogbf	ilogbl	logarithm function
	log	logf	logl	logarithm function
	log10	log10f	log10l	logarithm function
	log1p	log1pf	log1pl	logarithm function
	log2	log2f	log2l	logarithm function
	logb	logbf	logbl	logarithm function
matherr(S)	matherr	matherrl		error-handling function
remainder(S)	remainder	remainderf	remainderl	return floating point remainder of division of x by y
	remquo	remquof	remquol	return floating point remainder of division of x by y
rint(S)	llrint	llrintf	llrintl	return nearest integer value to floating point argument x
	llround	llroundf	llroundl	return the rounded integer value of x
	lrint	lrintf	lrintl	return nearest integer value to floating point argument x
	lround	lroundf	lroundl	return the rounded integer value of x
	rint	rintf	rintl	return nearest integer value to floating point argument x
	round	roundf	roundl	return the rounded integer value of x
	trunc	truncf	truncl	return the truncated integer value of x
sinh(S)	acosh	acoshf	acoshl	return inverse hyperbolic cosine of argument
	asinh	asinhf	asinhl	return inverse hyperbolic sine of argument
	atanh	atanhf	atanhl	return inverse hyperbolic tangent of argument
	cosh	coshf	coshl	return hyperbolic cosine of argument
	sinh	sinhf	sinhl	return hyperbolic sine of argument
	tanh	tanhf	tanhl	return hyperbolic tangent of argument
trig(S)	acos	acosf	acosl	return the arccosine of an argument in radians
	asin	asinf	asinl	return the arcsine of an argument in radians
	atan	atanf	atanl	return the arctangent of an argument in radians
	atan2	atan2f	atan2l	return the arctangent of y/x in radians
	cos	cosf	cosl	return the cosine of an argument in radians
	sin	sinf	sinl	return the sine of an argument in radians
	tan	tanf	tanl	return the tangent of an argument in radians