trusty (3) asinl.3posix.gz

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.

SEE ALSO

       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>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard for Information Technology -- 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 .