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MathGroup Archive 1994

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strange results of integration

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: strange results of integration
  • From: win at wisdom.weizmann.ac.il (Wiener Zvi)
  • Date: Fri, 7 Jan 94 12:28:31 +0200

Some strange results (isn't it a bug?): 

(* a normal probability distribution *)
In[1]:= p[x_, t_] = 1/(Sqrt[2Pi t])*Exp[-x^2/(2t)];

In[2]:= Integrate[ (Exp[s]-1)*p[s,h], {s,-Infinity, Infinity}]

On::none: Message SeriesData::csa not found.

Out[2]= 0

In[3]:= Integrate[ Exp[s]*p[s,h]-p[s,h], {s,-Infinity, Infinity}] 

               h/2       1
Out[3]= (-1 + E   ) Sqrt[-] Sqrt[h]
                         h

In[2] and In[3] are actually the same functions but the results are
different!! I also do not understand the Message.

Does anybody knows a simple way to get rid of Sqrt[1/h]*Sqrt[h]
assuming that h is real and positive, without Unprotect and
redefining Sqrt?


					Zvi Wiener,
					Dept.of Theor. Math.
					The Weizmann Inst. of Sc.
					Rehovot, 76100, Israel.





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