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C Library Functions  - besi (3)

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NAME

besi(3f) - [M_bessel] compute the I Bessel function for a given argument and order

CONTENTS

Synopsis
Description
Options
Example

SYNOPSIS

subroutine besi(X,N,BI,IER)

DESCRIPTION

Computes I Bessel function using series or asymptotic approximation depending on range of arguments.

    REMARKS

N and X must be .GE. zero

Checks for errors IN N and X and exits if any are present

    SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED

none

OPTIONS

Description of parameters

        X    The argument of the I Bessel function desired
        N    The order of the I Bessel function desired
        BI   The resultant I Bessel function
        IER  Resultant error code where

              IER=0 No error
              IER=1 N is negative
              IER=2 X is negative
              IER=3 underflow, BI .LT. 1.E-69, BI set to 0.0
              IER=4 overflow, X .GT. 170 where X .GT. N

EXAMPLE

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Nemo Release 3.1

besi (3)

June 29, 2025

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