FindRoot in 5.0
- To: mathgroup at smc.vnet.net
- Subject: [mg42819] FindRoot in 5.0
- From: emm10 at psu.edu (Eric Mockensturm)
- Date: Wed, 30 Jul 2003 04:07:53 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
I realize that FindRoot has changed but there seems to be a
fundamental difference in it between pre-5.0 versions and 5.0 that
breaks most of my notebooks. Maybe I've been following bad
'programming' practices all these years, but....
Anyway, a simple illustration follows.
In 4.2:
In[7]:=func[x_]:=(y=x;NIntegrate[BesselY[1/2,s],{s,1/2,y}])
In[8]:=FindRoot[(Print[x];func[x]),{x,2,4}]
Out[8]={x\[Rule]3.04729}
In 5.0:
In[1]:=func[x_]:=(y=x;NIntegrate[BesselY[1/2,s],{s,1/2,y}])
In[2]:=FindRoot[(Print[x];func[x]),{x,2,4}]
Out[2]={x\[Rule]4.}
with errors...
NIntegrate::nlim: s = x is not a valid limit of integration
It seems that 5.0 is trying to evaluate func[x] symbolically before
start to search for a root. How do I make a global change to this
behavior. Does it have something to do with the HoldAll attribute?
FindRoot was been HoldAll in 4.2, too.