### bessely =====================================================================

Tags
----
scripting, JS, internal, treenode, general concept

Parameters
----------
x,n

General description
-------------------

Bessel function of second kind.

###


Eval_bessely = ->
  push(cadr(p1))
  Eval()
  push(caddr(p1))
  Eval()
  bessely()

bessely = ->
  save()
  yybessely()
  restore()

#define X p1
#define N p2

yybessely = ->
  d = 0.0
  n = 0

  p2 = pop()
  p1 = pop()

  push(p2)
  n = pop_integer()

  if (isdouble(p1) && !isNaN(n))
    d = yn(n, p1.d)
    push_double(d)
    return
  
  if (isnegativeterm(p2))
    push_integer(-1)
    push(p2)
    power()
    push_symbol(BESSELY)
    push(p1)
    push(p2)
    negate()
    list(3)
    multiply()
    return

  push_symbol(BESSELY)
  push(p1)
  push(p2)
  list(3)
  return