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04-13-2013
12:34 PM

04-13-2013
12:34 PM

How to get the decision of integral in a symbolic form?

Mathematica gives an answer for indefinite integral. I got expression in the second line after the expansion of the limits. But I can`t plot with this expression. The plot appears for expression in the third line. Is it possible to get the decision of this integral any other way? Thank you.

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04-14-2013
04:09 AM

04-14-2013
04:09 AM

Re: How to get the decision of integral in a symbolic form?

According to Mathcad's numerical calculations the three expressions you have listed are all different! See attached.

You have three unspecified variables. Which do you want to plot against?

Why do you need a symbolic result if you just want plots - you could plot using numerics.

Alan

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04-14-2013
06:28 AM

04-14-2013
06:28 AM

Re: How to get the decision of integral in a symbolic form?

Thank for your answer. I need decision of integral in first line. A,b,c are constant and independent from variable x. I need plot result of this integral. So I can get result in simbolic form.

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04-14-2013
06:48 AM

04-14-2013
06:48 AM

Re: How to get the decision of integral in a symbolic form?

The integral in your file goes from 0 to infinity, so it has a single value. Do you mean the upper limit to be some finite value, x, and you want to plot the value of the integral as a function of this upper limit?

Alan

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04-14-2013
07:12 AM

04-14-2013
07:12 AM

Re: How to get the decision of integral in a symbolic form?

The primitive which iwill be got as a result of integration will be plotted from variable t which is included in c.

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04-14-2013
07:19 AM

04-14-2013
07:19 AM

Re: How to get the decision of integral in a symbolic form?

Then make c a function of t and simply plot the numerical result of the integral against t. If you post the values of a and b and the functional relationship between c and t, with the range of t-values of interest, I'll see if I can plot it.

Here is an example using arbitrary values

Alan

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04-14-2013
08:22 AM

04-14-2013
08:22 AM

Re: How to get the decision of integral in a symbolic form?

a=8.5*10^11, b=8*10^8, c=0.4-8*10^5*t. Range t is like this: -5*10^-9...+10^-6.

How does Mathematica give the primitive of this integral in symbolic form?

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04-14-2013
10:28 AM

04-14-2013
10:28 AM

Re: How to get the decision of integral in a symbolic form?

jvm jjjvb wrote:

How does Mathematica give the primitive of this integral in symbolic form?

You mean Mathcad, and it doesn't! Numerical results below:

Alan

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04-15-2013
02:56 AM

04-15-2013
02:56 AM

Re: How to get the decision of integral in a symbolic form?

I`d like c(t) to have discrete time as it is shown in the attached file. Which changes is it necessary to make?

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04-15-2013
05:58 AM

04-15-2013
05:58 AM

Re: How to get the decision of integral in a symbolic form?

There aren't any discrete times listed in this file! What are the times of interest?

Alan

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