## Linux and UNIX Man Pages

Test Your Knowledge in Computers #739
Difficulty: Medium
BASIC was based on FORTRAN II.
True or False?

# asinf(3) [posix man page]

```ASIN(P) 						     POSIX Programmer's Manual							   ASIN(P)

NAME
asin, asinf, asinl - arc sine function

SYNOPSIS
#include <math.h>

double asin(double x);
float asinf(float x);
long double asinl(long double x);

DESCRIPTION
These functions shall compute the principal value of the arc sine of their argument x. The value of x should be in the range [-1,1].

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.

RETURN VALUE
Upon successful completion, these functions shall return the arc sine of x, in the range [-pi/2,pi/2] radians.

For  finite  values  of	x not in the range [-1,1], 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 +-0, x 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.

If x is subnormal, a range error may occur and x should be returned.

ERRORS
These functions shall fail if:

Domain Error
The x argument is finite and is not in the range [-1,1],	  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.

These functions may fail if:

Range Error
The value of x is subnormal.

If  the	integer  expression  (math_errhandling	&  MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow floating-point exception shall be raised.

The following sections are informative.

EXAMPLES
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.

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

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
ogy -- Portable 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								   ASIN(P)```

## Check Out this Related Man Page

```LOG1P(P)						     POSIX Programmer's Manual							  LOG1P(P)

NAME
log1p, log1pf, log1pl - compute a natural logarithm

SYNOPSIS
#include <math.h>

double log1p(double x);
float log1pf(float x);
long double log1pl(long double x);

DESCRIPTION
These functions shall compute log_e(1.0 + x).

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.

RETURN VALUE
Upon successful completion, these functions shall return the natural logarithm of 1.0 + x.

If x is -1, a pole error shall occur and log1p(), log1pf(), and log1pl() shall return -HUGE_VAL, -HUGE_VALF, and -HUGE_VALL, respectively.

For  finite values of x that are less than -1,	 or if x is -Inf,  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 +-0, or +Inf, x shall be returned.

If x is subnormal, a range error may occur and x should be returned.

ERRORS
These functions shall fail if:

Domain Error
The finite value of x is less than -1,	or x 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.

Pole Error
The value of x is -1.

If  the	integer  expression  (math_errhandling	&  MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the integer expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the divide-by-zero floating-point exception shall be raised.

These functions may fail if:

Range Error
The value of x is subnormal.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set  to  [ERANGE].  If  the  integer	expression
(math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow floating-point exception shall be raised.

The following sections are informative.

EXAMPLES
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.