Re: Error in Bessel Zeros Package?
- To: mathgroup at christensen.cybernetics.net
- Subject: [mg311] Re: [mg298] Error in Bessel Zeros Package?
- From: Jerry Keiper <keiper>
- Date: Sun, 11 Dec 1994 15:00:13 -0600
You don't say what you defined fd[ ] to be, but there is clearly
no zero at 6.00731:
In[35]:= fd[15.96641939477542]
-17
Out[35]= 1.04083 10
In[36]:= fd[6.00731]
Out[36]= 0.0759842
Here is what I did:
------------------------------------------------------------------
nu = 3; l = 1.2;
jp[x_] = D[BesselJ[nu, x], x];
yp[x_] = D[BesselY[nu, x], x];
fd[x_] = jp[x] yp[l x] - jp[l x] yp[x];
Plot[fd[x], {x, 0, 20}]
Show[%, PlotRange -> {-1, 1}]
Plot[{jp[x] yp[l x], jp[l x] yp[x]}, {x, 0, 20}]
------------------------------------------------------------------
You will note that BesselJPrimeYPrimeJPrimeYPrimeZeros misses the
zero at
In[45]:= fd[2.730594863590175]
-17
Out[45]= -2.77556 10
In fact it appears that it always misses the first zero. This is
unfortunate and I will see what can be done to correct this.
Jerry B. Keiper
keiper at wri.com
Wolfram Research, Inc.