Re: NIntegrate & Integrate
- To: mathgroup at smc.vnet.net
- Subject: [mg100094] Re: NIntegrate & Integrate
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Fri, 22 May 2009 23:42:10 -0400 (EDT)
On 5/22/09 at 1:47 AM, kzhuravl at mtu.edu (Konstantin) wrote:
>Easy question for Mathematica. Evaluate definite integral: 2*Cos[x]
>from 8.76 to 4.56.
>I have evaluated it three different ways: Integrate, NIntegrate and
>Integral sign from basic math input palette.
>Here is the code(without Integral sign from basic math input
>palette):
>Clear[x]
>{a, b} = {8.76, 4.56};
>NIntegrate[2*Cos[x], {x, a, b}]
>Clear[x]
>Integrate[2*Cos[x], {x, a, b}]
>My output is:
>3.21059(NIntegrate)
>-3.21059(Integrate)
>The right answer is -3.21059.
>Why does NIntegrate gave me wrong answer?
I cannot reproduce your results above. I get the correct value
by simply pasting your code up to the line for NIntegrate into a
fresh session. That is:
In[1]:= {a, b} = {8.76, 4.56};
NIntegrate[2*Cos[x], {x, a, b}]
Out[2]= -3.21059
In[3]:= $Version
Out[3]= 7.0 for Mac OS X x86 (64-bit) (February 19, 2009)