# acos(3p) [centos man page]

ACOS(3P) POSIX Programmer's Manual ACOS(3P)PROLOG

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond- ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.NAME

acos, acosf, acosl - arc cosine functionsSYNOPSIS

#include <math.h> double acos(double x); float acosf(float x); long double acosl(long double x);DESCRIPTION

These functions shall compute the principal value of the arc cosine of their argument x. The value of x should be in the range [,1]. An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.-1RETURN VALUE

Upon successful completion, these functions shall return the arc cosine of x, in the range [0,pi] radians. For finite values of x not in the range [,1], a domain error shall occur, and either a NaN (if supported), or an implementation-defined value shall be returned. If x is NaN, a NaN shall be returned. If x is +1, +0 shall be returned. If x is +-Inf, a domain error shall occur, and either a NaN (if supported), or an implementation-defined value shall be returned.-1ERRORS

These functions shall fail if: Domain Error The x argument is finite and is not in the range [,1], or is +-Inf. If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised. The following sections are informative.-1EXAMPLES

None.APPLICATION USAGE

On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero.RATIONALE

None.FUTURE DIRECTIONS

None.SEE ALSO

cos(), feclearexcept(), fetestexcept(), isnan(), the Base Definitions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Con- ditions for Mathematical Functions, <math.h>COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogyPortable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .--IEEE

/The Open Group 2003 ACOS(3P)

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PROLOG

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond- ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.NAME

acos, acosf, acosl - arc cosine functionsSYNOPSIS

#include <math.h> double acos(double x); float acosf(float x); long double acosl(long double x);DESCRIPTION

These functions shall compute the principal value of the arc cosine of their argument x. The value of x should be in the range [,1]. An application wishing to check for error situations should set errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.-1RETURN VALUE

Upon successful completion, these functions shall return the arc cosine of x, in the range [0,pi] radians. For finite values of x not in the range [,1], a domain error shall occur, and either a NaN (if supported), or an implementation-defined value shall be returned. If x is NaN, a NaN shall be returned. If x is +1, +0 shall be returned. If x is +-Inf, a domain error shall occur, and either a NaN (if supported), or an implementation-defined value shall be returned.-1ERRORS

These functions shall fail if: Domain Error The x argument is finite and is not in the range [,1], or is +-Inf. If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised. The following sections are informative.-1EXAMPLES

None.APPLICATION USAGE

On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero.RATIONALE

None.FUTURE DIRECTIONS

None.SEE ALSO

cos(), feclearexcept(), fetestexcept(), isnan(), the Base Definitions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Con- ditions for Mathematical Functions, <math.h>COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogyPortable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .--IEEE

/The Open Group 2003 ACOS(3P)