acos(), acosf() arc cosine function	Function
	SYNOPSIS DESCRIPTION PARAMETERS RETURN VALUES CONFORMANCE MULTITHREAD SAFETY LEVEL PORTING ISSUES AVAILABILITY SEE ALSO

---

SYNOPSIS

#include <math.h>

double acos(double x)

float acosf(float x)

---

DESCRIPTION

The acos() and acosf() functions compute the principal value of the arc cosine of x in the range [0, Pi].

An application wishing to check for error situations should set errno to 0 before calling acos(). If errno is non-zero on return, or the value NaN is returned, an error has occurred.

The acosf() function is a single-precision version of acos().

---

PARAMETERS

x 

Value between -1 and +1 whose arc cosine is to be calculated.

---

RETURN VALUES

If |x|>1, acos(x) and acosf(x) return the following values based on the current math mode:

• In IEEE mode, NaN is returned.

• In POSIX mode, 0.0 is returned and errno is set to EDOM.

• In SVID or XOPEN mode, matherr() is called.

---

CONFORMANCE

acos(): ANSI/ISO 9899-1990

acosf(): PTC MKS Toolkit UNIX APIs extension

---

MULTITHREAD SAFETY LEVEL

MT-Safe.

---

PORTING ISSUES

None.

---

AVAILABILITY

PTC MKS Toolkit for Professional Developers
PTC MKS Toolkit for Professional Developers 64-Bit Edition
PTC MKS Toolkit for Enterprise Developers
PTC MKS Toolkit for Enterprise Developers 64-Bit Edition

---

SEE ALSO

Functions:

asin(), atan(), atan2(), cos(), cosh(), math(), matherr(), sin(), sinh(), tan(), tanh()

---

PTC MKS Toolkit 10.5 Documentation Build 40.