Integrate using Assumptions

• To: mathgroup at smc.vnet.net
• Subject: [mg81560] Integrate using Assumptions
• From: Art <grenander at gmail.com>
• Date: Wed, 26 Sep 2007 21:54:22 -0400 (EDT)

```When I change an integrand in a way that shouldn't affect the result,
mathematica is no longer able to map the integral to the built-in
function. Is there any way I can help it correctly recognize the form
of the function in general and in this particular case?

In[1]:= Integrate[ E^Cos[theta], {theta, 0, 2Pi} ]

Out[1]= 2 Pi BesselI[0, 1]

but

In[2]:= Integrate[ E^Cos[theta - theta0], {theta, 0, 2Pi},
Assumptions-
>Element[theta0, Reals]]

Cos[theta - theta0]
Out[2]= Integrate[E                   , {theta, 0, 2 Pi},

>    Assumptions -> theta0 \[Element] Reals]

or even

In[4]:= Integrate[E^Cos[theta-0.],{theta,0,2Pi}]

Cos[0. + theta]
Out[4]= Integrate[E               , {theta, 0, 2 Pi}]

```

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