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Student Support Forum: 'Legendre expasion rapresentation' topicStudent Support Forum > General > "Legendre expasion rapresentation"

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Andrea
03/30/10 11:49am

I'm doing some exercises on Legendre polynomial expansion to approximate a step function (in this simple case)

The algebra is working.
This is the formula for calculating the function that I need

Sum[(2 n + 1)/
2 Integrate[
If[x > 0.9, 10, 0] LegendreP[n, x], {x, -1, 1}] LegendreP[n,
x], {n, 0, 30}]


I'd like to represent the result which is a polynomial, a function in x.
If I use plot in front of this expression

Plot[Sum[(2 n + 1)/
2 Integrate[
If[x > 0.9, 10, 0] LegendreP[n, x], {x, -1, 1}] LegendreP[n,
x], {n, 0, 30}], {x, -1, 1}]
I get an error.

Where is my mistake?? Thank you



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Subject (listing for 'Legendre expasion rapresentation')
Author Date Posted
Legendre expasion rapresentation Andrea 03/30/10 11:49am
Re: Legendre expasion rapresentation Nasser M. Ab... 04/01/10 2:40pm
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