Re: NInegrate Bug

*To*: mathgroup at smc.vnet.net*Subject*: [mg116467] Re: NInegrate Bug*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Wed, 16 Feb 2011 04:36:12 -0500 (EST)

On 2/15/11 at 6:34 AM, tekolste at fastmail.net (Kurt TeKolste) wrote: >Has there been a resolution of the NIntegrate bug? >Apparently NIntegrate produces the negative of the right answer for >integrations that start and end to the left of zero -- some of the >time. >(Cos[x] and Sin[x^2] get the wrong result, Sin[x] is good). You didn't say what version you found this issue with. But based on the results I get below with Cos[x] and Sin[x^2] it appears the issue has is not present in version 8 In[1]:= NIntegrate[Cos[x], {x, -3/2, 3/2}] Out[1]= 1.99499 In[2]:= Integrate[Cos[x], {x, -3/2, 3/2}] Out[2]= 2 sin(3/2) In[3]:= % // N Out[3]= 1.99499 In[4]:= NIntegrate[Sin[x^2], {x, -3/2, 3/2}] Out[4]= 1.55648 In[5]:= Integrate[Sin[x^2], {x, -3/2, 3/2}] Out[5]= Sqrt[2*Pi]*FresnelS[3/Sqrt[2*Pi]] In[6]:= % // N Out[6]= 1.55648 In[7]:= Integrate[Sin[x^2], x] Out[7]= Sqrt[Pi/2]*FresnelS[Sqrt[2/Pi]*x] In[8]:= $Version Out[8]= 8.0 for Mac OS X x86 (64-bit) (November 6, 2010)