j0, j1, jn - Bessel functions of the first kind
The j0(), j1(), and jn() functions shall compute Bessel functions of x of the first kind of orders 0, 1, and n, respectively.
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.
Upon successful completion, these functions shall return the relevant Bessel value of x of the first kind.
If the x argument is too large in magnitude, or the correct result would cause underflow, 0 shall be returned and a range error may occur.
[MXX] If x is NaN, a NaN shall be returned.
These functions may fail if:
- Range Error
- The value of x was too large in magnitude, or an underflow occurred.
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.
No other errors shall occur.
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.
feclearexcept, fetestexcept, isnan, y0
XBD Treatment of Error Conditions for Mathematical Functions, <math.h>
First released in Issue 1. Derived from Issue 1 of the SVID.
The DESCRIPTION is updated to indicate how an application should check for an error. This text was previously published in the APPLICATION USAGE section.
The may fail [EDOM] error is removed for the case for NaN.
The RETURN VALUE and ERRORS sections are reworked for alignment of the error handling with the ISO/IEC 9899:1999 standard.
POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0350  is applied.
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