Math library (libm)

The math library, libm, contains the mathematics functions supplied by the C compilation system. This section describes some of the major functions,
organized by the manual page on which they appear. 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

exp(S)
exp	expf		Return e^x.
cbrt			Return cube root ofx.
log	logf		Return the natural logarithm of x. The value of x must be positive.
log10	log10f		Return the base-ten logarithm of x. The value of x must be positive.
pow	powf		Return x^y. If x is zero, y must be positive. If x is negative, y must be an integer.
sqrt	sqrtf		Return the non-negative square root of x. The value of x must be non-negative.
hypot(S)
hypot			Return sqrt(x x + y y), taking precautions against overflows.
gamma(S)
gamma	lgamma		Return ln(| (x)| ), where (x) is defined as $int from 0 to x e sup -t t sup x-1 dt$.
trig(S)
sin	sinf		Return, respectively, the sine, cosine, and tangent of x, measured in radians.
cos	cosf
tan	tanf
asin	asinf		Return the arcsine of x, in the range [-/2, +/2].
acos	acosf		Return the arccosine of x, in the range [0,+].
atan	atanf		Return the arctangent of x, in the range (-/2, +/2).
atan2	atan2f		Return the arctangent of y/x, in the range (-, +], using the signs of both arguments to determine the quadrant of the return value.
sinh(S)
sinh	sinhf		Return, respectively, the hyperbolic sine, cosine, and tangent of their argument.
cosh	coshf
tanh	tanhf
asinh acosh atanh			Return, respectively, the inverse hyperbolic sine, cosine, and tangent of their argument.
matherr(S)
matherr			Error handling.
erf(S)
erf			Returns the error function of x, defined as $ 2 over sqrt pi int from 0 to x e sup {-t sup 2}dt$.
erfc			erfc, which returns 1.0 - erf(x), is provided because of the extreme loss of relative accuracy if erf is called for large x and the result subtracted from 1.0 (for example, for x = 5, 12 places are lost).
floor(S)
floor	floorf		Return the largest integer not greater than x.
ceil	ceilf		Return the smallest integer not less than x.
copysign			Return x but with the sign of y.
fmod	fmodf		Return the floating point remainder of the division of x by y: x if y is zero, otherwise the number f with same sign as x, such that x = iy + f for some integer i, and | f |<| y |.
fabs	fabsf		Return the absolute value of x, | x |.
rint			Return the integer value nearest to the double-precision floating point argument x as a double-precision floating point number. The returned value is rounded according to the currently set machine rounding mode. If round-to-nearest (the default mode) is set and the difference between the function argument and the rounded result is exactly 0.5, then the result will be rounded to the nearest even integer.
remainder			Return the floating point remainder of the division of x by y: NaN if y is zero, otherwise the value r = x - yn, where n is the integer nearest the exact value of x. Whenever |n - x/y| = 1/2, then n is even.