DBESJ0, DBESJ1, DBESJN, DBESY0, DBESY1, DBESYN

Portability Functions: Compute the double-precision values of Bessel functions of the first and second kinds.

Module: USE DFPORT

Syntax

result = DBESJ0 (posvalu)
result = DBESJ1 (posvalu)
result = DBESJN (n, posvalu)
result = DBESY0 (posvalu)
result = DBESY1 (posvalu)
result = DBESYN (n, posvalu)

posvalue
(Input) REAL(8). Independent variable for a Bessel function. Must be greater than or equal to zero.

n
(Input) Integer. Specifies the order of the selected Bessel function computation.

Results:

DBESJ0, DBESJ1, and DBESJN return Bessel functions of the first kind, orders 0, 1, and n, respectively, with the independent variable posvalue.

DBESY0, DBESY1, and DBESYN return Bessel functions of the second kind, orders 0, 1, and n, respectively, with the independent variable posvalue.

Negative arguments cause DBESY0, DBESY1, and DBESYN to return a huge negative value.

Bessel functions are explained more fully in most mathematics reference books, such as the Handbook of Mathematical Functions (Abramowitz and Stegun. Washington: U.S. Government Printing Office, 1964). These functions are commonly used in the mathematics of electromagnetic wave theory.

Compatibility

CONSOLE STANDARD GRAPHICS QUICKWIN GRAPHICS WINDOWS DLL LIB

See Also: BESJ0, BESJ1, BESJN, BESY0, BESY1, BESYN

Example

    USE DFPORT
    real(8) besnum, besout
10  read *, besnum
    besout = dbesj0(besnum)
    print *, 'result is ',besout
    goto 10
    end