# jn(3) [posix man page]

J0(P)POSIX Programmer's Manual J0(P)NAME

j0, j1, jn - Bessel functions of the first kindSYNOPSIS

#include <math.h> double j0(double x); double j1(double x); double jn(int n, double x);DESCRIPTION

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.RETURN VALUE

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. If x is NaN, a NaN shall be returned.ERRORS

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. 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() , y0() , 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 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 J0(P)

## Check Out this Related Man Page

Y0(P)POSIX Programmer's Manual Y0(P)NAME

y0, y1, yn - Bessel functions of the second kindSYNOPSIS

#include <math.h> double y0(double x); double y1(double x); double yn(int n, double x);DESCRIPTION

The y0(), y1(), and yn() functions shall compute Bessel functions of x of the second 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.RETURN VALUE

Upon successful completion, these functions shall return the relevant Bessel value of x of the second kind. If x is NaN, NaN shall be returned. If the x argument to these functions is negative,or NaN shall be returned, and a domain error may occur. If x is 0.0,-HUGE_VALshall be returned and a range error may occur. If the correct result would cause underflow, 0.0 shall be returned and a range error may occur. If the correct result would cause overflow,-HUGE_VALor 0.0 shall be returned and a range error may occur.-HUGE_VALERRORS

These functions may fail if: Domain Error The value of x is negative. 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. Range Error The value of x is 0.0, or the correct result would cause overflow. 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 overflow floating-point exception shall be raised. Range Error The value of x is too large in magnitude, or the correct result would cause underflow. 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() , j0() , 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 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 Y0(P)