MathGroup Archive 1992

[Date Index] [Thread Index] [Author Index]

Search the Archive

More gaussian integration bugs

  • To: mathgroup at
  • Subject: More gaussian integration bugs
  • From: pmcguire at
  • Date: Wed, 8 Apr 92 09:56:22 EDT

 lsf at (Sam Finn) noted that the following incorrect
 occurred with Mathematica on a Sparcstation:
Mathematica version

The following integral is incorrect. The sign of the result is a clear
tip-off; moreover, it is a tabulated integral and can be found in
Gradshteyn & Ryzhik (3.462 4).

Mathematica 2.0 for SPARC
Copyright 1988-91 Wolfram Research, Inc.
 -- OPEN LOOK graphics initialized -- 

In[1]:= Integrate[x Exp[-(x-1)^2] , {x, -Infinity, Infinity}]

                                         3  3
        -(2 E Sqrt[Pi] + HypergeometricU[-, -, 1])
                                         2  2
Out[1]= ------------------------------------------
                           2 E

In[2]:= N[%]

Out[2]= -1.86153

The difficulty seems to be machine dependent as I got the correct result
using Mathematica 2.0 on a MacIIcx with no problem.  To recognize this as
the correct answer it is easy to see the integral is the same as

Integrate[x Exp[-(x-1)^2] , {x, -Infinity, Infinity}]

Paul McGuire
pmcguire at

  • Prev by Date: Determinant function in Mathematica
  • Next by Date: Re: Determinant function in Mathematica
  • Previous by thread: More gaussian integration bugs
  • Next by thread: Re:More gaussian integration bugs