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Student Support Forum: 'Problem with mapping. Probably a basic problem' topicStudent Support Forum > General > Archives > "Problem with mapping. Probably a basic problem"

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Author Comment/Response
Max
10/16/12 10:07pm

What I'm doing is integrating some big nasty function with respect to r from limits 0 to L, and that integral = .9, and I'm using FindRoot to find what L is. L changes depending on what z is, so I'm trying to map a table of L and its corresponding z. But what I keep getting is just the same L and z, and then obviously the list plot is just one point.

I've learned all the Mathematica I know in the last 5 hours, so I'm not really sure how to find what I'm doing wrong. I know everything up until FindRoot works, because if I just run that and manually put z=1 or z=2, I get correct outputs, but something about the zrange or map or whatever is not working right.

Here's the code:

data = Map[{z,
FindRoot[
Integrate[
1/14 (r^2) (((2 (z^(3/2)) E^(-z*r))^2) +
9 (((1/(3^.5)) ((z/2)^(3/2)) (z*r) (E^(-(z*r)/2)))^2) +
4 ((2/27) ((2/5)^.5) ((z/3)^(3/2)) ((z*r)^2) (E^(-(z*r)/
3)))^2), {r, 0, L}] == .9, {L, 1}][[1]][[2]]} &,
zrange]


And here's a picture of what happens:

http://i10.photobucket.com/albums/a138/iammax/mathematicaproblem.png

As you can see, the output is just {{1,L(1)} repeating, when what I want is {{1,L(1),{2,{L(2)}}, etc

I think what I need is a way for the Range command to iterate the variable z, such that if I do Range[z=1,z=5] or something similar, it maps the thing from z=1, then z=2, then z=3, etc. I'm not sure how to do this.

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Subject (listing for 'Problem with mapping. Probably a basic problem')
Author Date Posted
Problem with mapping. Probably a basic problem Max 10/16/12 10:07pm
Re: Problem with mapping. Probably a basic prob... Bill Simpson 10/17/12 11:38am
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