besj1(3f) - [M_bessel] calculates the Bessel function J(X) of order one.
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Example
function besj1(xx)
Series evaluation is used for small arguments, recurrence techniques are used for midrange, and Hankel-S asymptotic expansion is used for large arguments. Accuracy is between thirteen and fourteen correct significant figures except for large arguments where the accuracy eventually falls to eight figures.
X may be any doubleprecision argument
Origin
Sandia Mathematical Program Library Applied Mathematics Division 2642 Sandia Laboratories P. O. Box 5800 Albuquerque, New Mexico 87115 Control Data 6600 Version 5.1, 10 December 1973Written by Ronald D. Halbgewachs, October 1,1971.
Changes were made for portability and to conform to newer Fortran standards.
besj1 (3) | March 11, 2021 |