BSY0

This function evaluates the Bessel function of the second kind of order zero.

Function Return Value

BSY0 — Function value. (Output)

Required Arguments

X — Argument for which the function value is desired. (Input)

FORTRAN 90 Interface

Generic: BSY0 (X)

Specific: The specific interface names are S_BSY0 and D_BSY0.

FORTRAN 77 Interface

Single: BSY0 (X)

Double: The double precision function name is DBSY0.

Description

The Bessel function Y0(x) is defined to be

 

To prevent the answer from being less accurate than half precision, x should be smaller than

 

For the result to have any precision at all, ∣x∣ must be less than 1/ɛ. Here, ɛ is the machine precision, ɛ = AMACH(4).

 

Figure 1,  Plot of Y0(x) and Y1(x)

Example

In this example, Y0(3.0) is computed and printed.

 

USE BSY0_INT

USE UMACH_INT

 

IMPLICIT NONE

! Declare variables

INTEGER NOUT

REAL VALUE, X

! Compute

X = 3.0

VALUE = BSY0(X)

! Print the results

CALL UMACH (2, NOUT)

WRITE (NOUT,99999) X, VALUE

99999 FORMAT (' BSY0(', F6.3, ') = ', F6.3)

END

Output

 

BSY0( 3.000) = 0.377