- assigned_to: nobody --> rtoy
Hello, Maxima team. I'm a new user and am amazed with
what I'm able to accomplish in Maxima.
I'm having a little trouble. I'm trying to make a
bessel function plot, and it keeps failing. For instance:
(C1)
plot3d(bessel_j[0](x),[x,0,10],[y,0,2*%pi],['transform_xy,polar_to_xy]);
Error: ((MQAPPLY SIMP) (($BESSEL_J SIMP ARRAY) 0)
0.33333333333333331) is not of type (OR RATIONAL
LISP:FLOAT).
Fast links are on: do (si::use-fast-links nil) for
debugging
Error signalled by LISP:FLOAT.
Broken at LISP:FLOAT. Type :H for Help.
Nothing I do seems to allow the plot to complete,
including using BESSELEXPAND and making the order 1/2:
(C1) besselexpand:true;
(D1) TRUE
(C2)
plot3d(bessel_j[1/2](x),[x,0.0001,10],[y,0,2*%pi],['transform_xy,polar_to_xy]);
Error: ((MTIMES SIMP) 0.0099999999833333339 ((MEXPT
SIMP) 2 (# 1 2)) ...) is not of type (OR RATIONAL
LISP:FLOAT).
Fast links are on: do (si::use-fast-links nil) for
debugging
Error signalled by LISP:FLOAT.
Broken at LISP:FLOAT. Type :H for Help.
My maxima information:
-------------------------------------------------------------
Maxima version: 5.9.0
Maxima build date: 22:24 2/9/2003
host type: i386-redhat-linux-gnu
lisp-implementation-type: Kyoto Common Lisp
lisp-implementation-version: GCL-2-5.0
-------------------------------------------------------------
(I'm using the Redhat RPMs on Redhat 8.0.)
A bug fix would be great, but if it's not possible, I
really would like to get a workaround, as I'd like to
get a picture of the plot for a paper. If there is a
simple workaround, could you please let me know?
Logged In: YES
user_id=28849
Yes, this is a bug in bessel_j wherein it doesn't give a
numerical answer even when the arg is a float.
As a workaround, use j0(x) insetad of bessel_j[0](x).
Or you can set numer:true before plotting, or use
plot3d(bessel_j[0](x),[x,0,10],[y,0,2*%pi],['transform_xy,polar_to_xy]), numer;
Logged In: YES
user_id=719178
Thank you very much! Using numer:true; works great. The
plots look very pretty.
You can consider this bug closed as far as I'm concerned
(but maybe you might want to keep it open at a lower
priority, in case you might want to fix bessel_j in the
future...). Thanks again.
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