math.h

math.h is a header file in the Standard C Library of the C programming language . It was developed for mathematical functions. The programming language C ++ also uses the functions to ensure the compatibility of C to C ++, and declares them in the header file cmath (used there without the file extension “.h”).

All functions that read in or output an angle work with radians . Most functions work with floating point numbers . Mathematical functions with integer values ( Integer work) as abv, labs, div or ldiv, are instead in the header file stdlib.h represented.

Functions up to C95

The following functions were declared in the standards up to and including C95 .

Surname	description	Mathematical formulation
acos	Arccosine	${\displaystyle \arccos x}$
asin	Arcsine	${\displaystyle \arcsin x}$
atan	Arctangent	${\displaystyle \arctan x}$
atan2	"Arctangent" with two arguments	${\displaystyle \operatorname {atan2} (y,x)}$
ceil	Rounding function	${\displaystyle \lceil x\rceil }$
cos	cosine	${\displaystyle \cos x}$
cosh	Hyperbolic cosine	${\displaystyle \cosh x}$
exp	Exponential function	${\displaystyle e^{x}}$
fabs	Amount function	${\displaystyle |x|}$
floor	Full part function	${\displaystyle \lfloor x\rfloor }$
fmod	Executes the modulo function for floating point numbers	${\displaystyle x{\bmod {y}}}$
frexp	Divides a floating point number into a factor and a power with base 2
ldexp	Multiplies the first parameter by 2 raised to the power of the second parameter	${\displaystyle x2^{y}}$
log	Natural logarithm	${\displaystyle \ln x}$
log10	Logarithm to base 10	${\displaystyle \log _{10}x}$
modf	Splits a floating point number into two numbers, before and after the decimal point
pow	Exponentiates the first with the second parameter	${\displaystyle x^{y}}$
sin	Sine	${\displaystyle \sin x}$
sinh	Hyperbolic sine	${\displaystyle \sinh x}$
sqrt	square root	${\displaystyle {\sqrt {x}}}$
tan	tangent	${\displaystyle \tan x}$
tanh	Hyperbolic tangent	${\displaystyle \tanh x}$

C99 functions

With the C99 standard , math.h was expanded to include the following functions.

Surname	description	Mathematical formulation
acosh	Hyperbolic areakosine	${\displaystyle \operatorname {arcosh} x}$
asinh	Hyperbolic area	${\displaystyle \operatorname {arsinh} x}$
atanh	Hyperbolic areatangens	${\displaystyle \operatorname {artanh} x}$
cbrt	Cube root	${\displaystyle {\sqrt[{3}]{x}}}$
copysign(x,y)	returns the value of x with the sign of y back	${\displaystyle |x|\cdot \operatorname {sgn} y}$
erf	Error function	${\displaystyle \operatorname {erf} x}$
erfc	Returns the complementary error of x back	${\displaystyle \operatorname {erfc} x}$
exp2(x)	Power 2 with the transferred parameter	${\displaystyle 2^{x}}$
expm1(x)	Returns the value of exp () - 1 return	${\displaystyle e^{x}-1}$
fdim(x,y)	Positive difference	${\displaystyle \max(0,x-y)}$
fma(x,y,z)	Multiplied and added	${\displaystyle xy+z}$
fmax(x,y)	maximum	${\displaystyle \max(x,y)}$
fmin(x,y)	minimum	${\displaystyle \min(x,y)}$
hypot(x,y)	hypotenuse	${\displaystyle {\sqrt {(x^{2}+y^{2})}}}$
ilogb	how logb, however, gives intback	(int)logb(x)
lgamma	Logarithm of the gamma function	${\displaystyle \ln |\Gamma (x)|}$
llrint	Rounding function
lrint	Rounding function
llround	Rounding function
lround	Rounding function
log1p(x)	Natural logarithm of 1 + x	${\displaystyle \ln(1+x)}$
log2	Logarithm to base 2	${\displaystyle \operatorname {lb} x}$
logb	Returns the integer exponent of a floating point number as a floating point number	${\displaystyle \operatorname {rint} (\log _{\mathrm {FLT\_RADIX} }|x|)}$
nan(s)	A NaN produce	${\displaystyle 0/0}$
nearbyint	Rounds floating point numbers to the nearest integer
nextafter(x,y)	Returns the next representable number after x (direction y )
nexttoward(x,y)	Just like nextafter, except for y , is always long doublereturned as
remainder(x,y)	Remainder of a division
remquo(x,y,p)	Same as remainder, but stores the quotient (as int) as the destination of the pointer p
rint	Rounds to the nearest integer, depending on the rounding mode, returns a floating point number
round	commercial rounding function	${\displaystyle \lfloor x+0{,}5\rfloor }$
scalbln(x,y)	x * FLT_RADIXy ( y is long)	${\displaystyle x\cdot \mathrm {FLT\_RADIX} ^{y}}$
scalbn(x,y)	x * FLT_RADIXy ( y is int)	${\displaystyle x\cdot \mathrm {FLT\_RADIX} ^{y}}$
tgamma	Gamma function	${\displaystyle \Gamma (x)}$
trunc	Trims a floating point number, i.e. H. rounds "towards zero"	${\displaystyle {\begin{cases}\lfloor x\rfloor ,&x\geq 0\\\lceil x\rceil ,&x<0\end{cases}}}$

example

1 #include <stdio.h>
2 #include <math.h>
3 
4 int main() {
5     double a = 5, b = 4;
6     double c = pow(a, b);
7     printf("%f hoch %f ist %f\n", a, b, c);
8 }

Web links

• Rationale for International Standard - Programming Languages ​​- C. (PDF, 898 kB) Retrieved September 4, 2011 (C99). 
• Description on cplusplus.com (English)
• Documentation from math.h on dinkumware.com ( Memento from February 21, 2010 in the Internet Archive )