• To: mathgroup at smc.vnet.net
• Subject: [mg71419] Re: About NIntegrate
• From: "Evanescence" <origine26 at yahoo.com.tw>
• Date: Fri, 17 Nov 2006 04:30:56 -0500 (EST)
• References: <ejf0mv\$3qv\$1@smc.vnet.net><ejh0m2\$96e\$1@smc.vnet.net>

```Dear Mr. Dimitris:
Very thank you the suggestions that you give me. I will remember in my mind.
The Function of P[a] is the integration form that cannot more simplify
it ,because I will solve the NIntegrate[P[a]*G[a]] so seem to cannot
NInitegrate P[a] at the first.
Very thank you you look my question and answer it .

Regards.
Evanescence.

dimitris ¼g¹D¡G

> Before you start working with Mathematica you should try to LEARN it
> syntax.
> All programming languages have theis syntax rules, why you believe
> Mathematica is an exception?
>
> Here is good place to start:
> Copy/Paste the following command in a Mathematica notebook and then
> execute it.
>
> Here are also some things to notice:
>
> Do not mix exact and non exact numbers like 3 with 0.3; use 3/10 for
> For your integral the correct form of the iterator is {variable,lower
> limit, upper limit}
>
> Note you much treat Numerical Integration as an interactive object; for
> example plot the functions to be NIntegrated before
> you call the command. Are there any singularities in the integration
> range?
>
> Since you want a numerical estimate and not a symbolic result don't use
> Integrate; try NIntegrate in the definition of P.
>
> For users of introductory level I always suggest to avoid defining
> functions with Capital letters.
>
> Regards
> Dimitris
>
> Evanescence wrote:
> > Dear all: My question is as follows:
> >
> > First I definite one variable is: a=Cosh[b]
> > then,I definite two functions:
> > one is :
> > P[a_]=(((2)^(1/2))/Pi)*Integrate[(Cosh[I*t])/((a-Cosh[t])^^(1/2)),0,b,t]
> >   ! (I is the (-1)^(1/2)) ,the upper limit is b, the lower limit is 0)
> > another
> > is:G[a_]=((-(a-Cos[0.5])^(-3/2))/(3*(10)^2))*(Sin[0.5])^(2)+(1/1-0.5*0.1)*((0.025*(1+Cos[0.5])+0.4/999)*(1+Cos[0.5])^(1/2)*(ArcTan[(a-Cos[0.5])^(1/2)/(1+Cos[0.5])^(1/2)]-Pi/2)+(0.025*(1-Cos[0.5])-0.4/999)*(1+Cos[0.5])^(1/2)*(ArcTanh[(1-Cos[0.5])^(1/2)/(a-Cos[0.5])^(1/2)])
> >
> > then
> > NIntegrate[P[a]*G[a],{a,1,Infinity}]
> > but get error message is NIntegrate P[a]*G[a] is not numerical at
> > {a}={2.}
> > so,please solve my confuse,thank you!
> >
> > Evanescence 2006/11/15

```

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