Manuals/calci/BESSELJ

BESSELJ(x,n)

• $x$ is the value to evaluate the function
• $n$ is the order of the Bessel function and is an integer

Description

• This function gives the value of the modified Bessel function.
• Bessel functions is also called Cylinder Functions because they appear in the solution to Laplace's equation in cylindrical coordinates.
• Bessel's Differential Equation is defined as: $x^{2}{\frac {d^{2}y}{dx^{2}}}+x{\frac {dy}{dx}}+(x^{2}-\alpha ^{2})y=0$

where α is the arbitrary complex number.

• But in most of the cases α is the non-negative real number.
• The solutions of this equation are called Bessel Functions of order n.
• Bessel functions of the first kind, denoted as Jn(x), and
• The Bessel function of the first kind of order can be expressed as: Jn(x)=summation(k=0 to infinity){(-1)^k(x/2)^n+2k}/k!gamma(n+k+1), where gamma(n+k+1)=(n+k)! or *Integral 0 to infinity x^(n+k).e^-x dx. is the gamma function.
• This function will give the result as error when 1.x or n is non numeric 2. n<0, because n is the order of the function

Examples

1. BESSELJ(2,3)=0.12894325(EXCEL)Jn(x)=0.10728467204(calci)J1(x)0.5767248079(Actual)J1(x)
2. BESSELJ(7,2)=-0.301417224(EXCEL)Jn(x)=NAN(calci)=-0.0046828257(Actual)J1(x)
3. BESSELJ(5,1)=-0.327579139(EXCEL)Jn(x)=NAN(calci)

See Also

• BESSELI
• BESSELK
• BESSELY

References

Absolute_value