j1(), j1f()

Compute a Bessel function of the first kind of order 1


#include <math.h>

double j1( double x );

float j1f( float x );


The number that you want to compute the Bessel function for.


The general-purpose math library.
(QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.


These functions compute the Bessel function for x of the first kind of order 1.

To check for error situations, use feclearexcept() and fetestexcept(). For example:


The Bessel value of x of the first kind of order 1.

If: These functions return: Errors:
x is ±0.0 0.0, with the same sign as x
x is ±Inf 0.0, with the same sign as x
x is NaN NaNNaN
The correct result would cause underflow 0.0 FE_UNDERFLOW

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.


j1() is POSIX 1003.1 XSI; j1f() is Unix

Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes