[Maxima-bugs] [ maxima-Bugs-736538 ] bessel_j with floating point argument

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Bugs item #736538, was opened at 2003-05-12 12:26
Message generated for change (Comment added) made by rtoy
You can respond by visiting: 
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Category: None
Group: None
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Barton Willis (willisb)
>Assigned to: Raymond Toy (rtoy)
Summary: bessel_j with floating point argument

Initial Comment:
The function bessel_j misbehaves with a floating point 
argument

(C1) bessel_j(0.2,3);

Error: #C(0.20000000000000001 0.0) is not of type (OR 
RATIONAL LISP:FLOAT).
Fast links are on: do (si::use-fast-links nil) for debugging
Error signalled by MACSYMA-TOP-LEVEL.
Broken at MACSYMA-TOP-LEVEL.  Type :H for Help.
MAXIMA>>:q
(C2) build_info();

Maxima version: 5.9.0
Maxima build date: 19:10 2/9/2003
host type: i686-pc-mingw32
lisp-implementation-type: Kyoto Common Lisp
lisp-implementation-version: GCL-2-5.0

Evaluation took 0.00 seconds (0.00 elapsed)

This is caused by $bessel receiving a lisp complex 
number as its first argument -- it expects a Maxima 
number instead. A possible fix is to change

(defun $bessel_j (arg order)
  (if (and (numberp order)
	   (numberp ($realpart arg))
	   (numberp ($imagpart arg)))
      ($bessel (complex ($realpart arg) ($imagpart arg)) 
order)
      (subfunmakes '$bessel_j (ncons order) (ncons arg))))

to

(defun $bessel_j (arg order)
  (if (and (numberp order)
	   (numberp ($realpart arg))
	   (numberp ($imagpart arg)))
      ($bessel arg order)            
      (subfunmakes '$bessel_j (ncons order) (ncons arg))))

Barton

----------------------------------------------------------------------

>Comment By: Raymond Toy (rtoy)
Date: 2003-05-12 23:20

Message:
Logged In: YES 
user_id=28849

This should be fixed now, in the way you suggest.

This brings up an important issue:  What is the right way to
call Bessel_J?  Is it 

bessel_j(x, n) or bessel_j[n](x)

Discussion moved to mailing list.

----------------------------------------------------------------------

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