Re: Integration Problem

• To: mathgroup at smc.vnet.net
• Subject: [mg126369] Re: Integration Problem
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Fri, 4 May 2012 06:25:55 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```On 5/3/12 at 4:34 AM, michael.musheghian at gmail.com (Michael
Musheghian) wrote:

>I found that evaluation of this 2 integrals yield a bit different
>result. What could be the reason?

>Integrate[E^(-1/10 ((1 + r2z)^2)), {r2z, -Infinity, Infinity}]

>Integrate[E^(-0.1 ((1 + r2z)^2)), {r2z, -Infinity, Infinity}]

The first gives an exact result, the second a numerical approximation. The
small complex component of

In[2]:= Integrate[E^(-0.1 ((1 + r2z)^2)), {r2z, -Infinity, Infinity}]

Out[2]= 5.60499 -2.03152*10^-16 I

is the result of small errors introduced by imprecise values. Do

In[3]:= Chop@
Integrate[E^(-0.1 ((1 + r2z)^2)), {r2z, -Infinity, Infinity}]

Out[3]= 5.60499

to get rid of it.

```

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