algebrite/sources/bessely.coffee

Computer Algebra System in Coffeescript

#-----------------------------------------------------------------------------
#
#	Bessel Y function
#
#	Input:		tos-2		x	(can be a symbol or expr)
#
#			tos-1		n
#
#	Output:		Result on stack
#
#-----------------------------------------------------------------------------



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) && n != 0x80000000)
		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