Calculate Spherical Bessel Function yv(z)

Online calculator for computing the spherical Bessel function of the second kind

Spherical Bessel-Y Function Calculator

Spherical Neumann Function

The yv(z) or spherical Neumann function shows singular behavior at the origin and is the second solution in spherical coordinates.

Order of the spherical Neumann function
Function argument (z > 0)
X-axis scaling
Result
yv(z):

Spherical Bessel-Y Function Curve

Mouse pointer on the graph shows the values.
The spherical Neumann function shows singularities at the origin and large oscillations.

Properties of the Spherical Neumann Function

The spherical Neumann function is the second linearly independent solution:

  • Singularity: yv(z) → -∞ for z → 0
  • Relation to Yv: yv(z) = √(π/2z) Yv+1/2(z)
  • Asymptotic behavior: Oscillation with 1/z damping
  • Physical meaning: Outgoing waves
  • Combination with jv: General solution possible
  • Application: Scattering problems and boundary conditions

Spherical Neumann Functions in Physics

The spherical Neumann function forms a complete solution system with jv:

General Solution
\[R_l(kr) = A j_l(kr) + B y_l(kr)\]

Linear combination of both solutions

Hankel Functions
\[h_l^{(\pm)}(kr) = j_l(kr) \pm i y_l(kr)\]

Incoming and outgoing waves

Formulas for the Spherical Neumann Function

Definition via Classical Neumann Function
\[y_\nu(z) = \sqrt{\frac{\pi}{2z}} Y_{\nu+1/2}(z)\]

Relation to the classical Neumann function Yν

Explicit Expressions for Small Orders
\[y_0(z) = -\frac{\cos z}{z}, \quad y_1(z) = -\frac{\cos z}{z^2} - \frac{\sin z}{z}\]

Simple trigonometric representation with singularity

Asymptotic Form
\[y_\nu(z) \sim \frac{1}{z} \sin\left(z - \frac{(\nu+1)\pi}{2}\right)\]

For large z (90° phase shift to jν)

Wronskian Determinant
\[W[j_\nu(z), y_\nu(z)] = j_\nu(z) y'_\nu(z) - j'_\nu(z) y_\nu(z) = \frac{1}{z^2}\]

Proof of linear independence

Recurrence Formulas
\[\frac{2\nu+1}{z} y_\nu(z) = y_{\nu-1}(z) + y_{\nu+1}(z)\] \[\frac{d}{dz} y_\nu(z) = \frac{\nu}{z} y_\nu(z) - y_{\nu+1}(z)\]

Identical to jν (same differential equation)

Special Properties

Singularity at Origin
\[\lim_{z \to 0} y_\nu(z) = -\infty\]

For all ν ≥ 0

Important Values
y₀(π/2) = 0 y₁(π) = 1/π y₀(π) = 0
Zeros of y₀
π/2, 3π/2, 5π/2, ...

Zeros at odd multiples of π/2

Behavior for Large z
yν(z) ≈ (1/z) sin(z - (ν+1)π/2)

Oscillation with 1/z damping

Application Areas

Scattering problems, outgoing waves, boundary conditions for infinite domains.

Description and Formulas

The spherical Bessel functions are a special class of functions that play an important role in physics and mathematics. They are solutions to the Bessel differential equation, which represents the radial part of the Laplace equation with cylindrical or spherical symmetry.

Bessel Functions of the First Kind (Jν)

These functions are solutions to the Bessel differential equation and are often called cylinder functions. The Bessel function of the first kind of order n is defined as:

\(\displaystyle J_{\nu}(x) = \frac{(x/2)^{\nu}}{\Gamma(\nu + 1)} \, {}_0F_1(; \nu + 1; -x^2/4) \)

Here \(\Gamma(\nu + 1)\) is the gamma function and \(\nu\) is a real or complex number. These functions occur in various physical problems, such as studying the natural vibrations of a circular membrane, heat conduction in rods, or field distribution in circular waveguides.

Spherical Bessel Functions (jμ)

These functions are special Bessel functions that occur in spherical geometry. They are solutions to the Helmholtz equation in spherical coordinates. The spherical Bessel function jμ is defined as:

\(\displaystyle j_{\mu}(x) = \sqrt{\frac{\pi}{2x}} J_{\mu+1/2}(x) \)

Here \(\mu\) is an integer or half-integer order. Spherical Bessel functions are used, for example, in describing electromagnetic waves in spherical coordinates.

Spherical Neumann Functions (yμ)

Spherical Neumann functions are analogous to spherical Bessel functions, but with a different definition. They also occur in spherical geometry. They are defined as:

\(\displaystyle y_\mu(z) = \sqrt{\frac{\pi}{2z}} Y_{\mu+1/2}(z) \)

where \(Y_\mu(z)\) is the Bessel function of the second kind (Neumann function). These functions show singular behavior at the origin and are important for scattering problems.

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