Integration bug?
- To: mathgroup at thnext.mit.edu
- Subject: Integration bug?
- From: Robert Singleton <bobs at thnext.mit.edu>
- Date: Thu, 1 Apr 93 13:32:14 -0500
Hello,
Does anyone know what's going on here? I do the following integral
In[14]:=
Integrate[Log[x]/((x-y)(x-z)),{x,0,Infinity}]
Out[14]=
0
So this vanishes for every y and z. This seemed funny to me so I
tried y=1 and z=2. Here is what I got
In[15]:=
Integrate[Log[x]/((x-1)(x-2)),{x,0,Infinity}]
Out[15]=
1 2
-Log[-]
2
--------
2
What's going on?!? I got the following answer for
In[16]:=
Integrate[Log[x]/((x+y)(x+z)),{x,0,Infinity}]
Out[16]=
2 2
-Log[y] + Log[z]
------------------
2 (-y + z)
I've checked this from tables and I believe it's correct. So Mma is
doing something right. But what? I suspect the trouble is in Mma
not knowing whether y and z are positive or negative. But I'm not
sure. Any help would be greatly appreciated. thanks.
bob singleton
bobs at thnext.mit.edu