bug? ratinterpol generates 0^0 / pattern matching



Hello Maxima Mailinglist,

the following use of ratinterpol generates 0^0.
Is this a bug or a feature?

I have some hundred! similar ones!
I only know that the expressions are rational functions that's all :-(

Could this perhaps be done with pattern matching?

Best Regards
Andre Maute

------------------------------------------------------------------
display2d : false;

h00 : 1*(-1/((b3+1)*(2*b3-1)));
h01 : 1*(-(4*b3+3)/((b3+2)*(2*b3-1)*(2*b3+3)));
h02 : 1*(-6*(b3+1)*(2*b3+3)/((b3+2)*(2*b3-1)*(2*b3+5)^2));
h03 : 1*(-2*(2*b3+3)*(4*b3+5)/((b3+3)*(2*b3-1)*(2*b3+5)*(2*b3+7)));
h04 : 1*(-5*(2*b3+3)^2/((b3+3)*(2*b3-1)*(2*b3+7)*(2*b3+9)));
h05 : 1*(-3*(2*b3+3)*(4*b3+7)/((b3+4)*(2*b3-1)*(2*b3+7)*(2*b3+11)));

h0 :[
[0,h00],
[1,h01],
[2,h02],
[3,h03],
[4,h04],
[5,h05]
];

load(interpol);
ratinterpol(h0,1,varname='b2);
-------------------------------------------------------------------
~$ maxima -b ratinterpol.max 
Maxima 5.19.1 http://maxima.sourceforge.net
Using Lisp SBCL 1.0.18.debian
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1)                       batch(ratinterpol.max)

batching /home/user/ratinterpol.max
(%i2)                          display2d : false
(%o2) false
(%i3) h00:1*(-1)/((1+b3)*(2*b3-1))
(%o3) -1/((b3+1)*(2*b3-1))
(%i4) h01:1*(-(3+4*b3))/((2+b3)*(2*b3-1)*(3+2*b3))
(%o4) (-4*b3-3)/((b3+2)*(2*b3-1)*(2*b3+3))
(%i5) h02:1*(-6*(1+b3)*(3+2*b3))/((2+b3)*(2*b3-1)*(5+2*b3)^2)
(%o5) -6*(b3+1)*(2*b3+3)/((b3+2)*(2*b3-1)*(2*b3+5)^2)
(%i6) h03:1*(-2*(3+2*b3)*(5+4*b3))/((3+b3)*(2*b3-1)*(5+2*b3)*(7+2*b3))
(%o6) -2*(2*b3+3)*(4*b3+5)/((b3+3)*(2*b3-1)*(2*b3+5)*(2*b3+7))
(%i7) h04:1*(-5*(3+2*b3)^2)/((3+b3)*(2*b3-1)*(7+2*b3)*(9+2*b3))
(%o7) -5*(2*b3+3)^2/((b3+3)*(2*b3-1)*(2*b3+7)*(2*b3+9))
(%i8) h05:1*(-3*(3+2*b3)*(7+4*b3))/((4+b3)*(2*b3-1)*(7+2*b3)*(11+2*b3))
(%o8) -3*(2*b3+3)*(4*b3+7)/((b3+4)*(2*b3-1)*(2*b3+7)*(2*b3+11))
(%i9) h0:[[0,h00],[1,h01],[2,h02],[3,h03],[4,h04],[5,h05]]
(%o9) [[0,-1/((b3+1)*(2*b3-1))],[1,(-4*b3-3)/((b3+2)*(2*b3-1)*(2*b3+3))],
       [2,-6*(b3+1)*(2*b3+3)/((b3+2)*(2*b3-1)*(2*b3+5)^2)],
       [3,-2*(2*b3+3)*(4*b3+5)/((b3+3)*(2*b3-1)*(2*b3+5)*(2*b3+7))],
       [4,-5*(2*b3+3)^2/((b3+3)*(2*b3-1)*(2*b3+7)*(2*b3+9))],
       [5,-3*(2*b3+3)*(4*b3+7)/((b3+4)*(2*b3-1)*(2*b3+7)*(2*b3+11))]]
(%i10) load(interpol)
(%o10) "/home/puck/opt/maxima/share/maxima/5.19.1/share/numeric/interpol.mac"
(%i11) ratinterpol(h0,1,varname = 'b2)
0^0 has been generated
#0: ratinterpol(tab=[[0,-1/((b3+1)*(2*b3-1))],[1,
(-4*b3-3)/((b3+2)*(2*b3-1)*(2*b3+3))],
[2,-6*(b3+1)*(2*b3+3)/((b3+2)*(2*...,r=1,select=[varname = b2])(interpol.mac 
line 324)
 -- an error.  To debug this try debugmode(true);
(%o11) "/home/user/ratinterpol.max"
-------------------------------------------------------------------