What's wrong with this MATLAB code for Rutherford scattering, it won't run for me!

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  • #1
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What's wrong with this MATLAB code for Rutherford scattering, it won't run for me! :(

Hi,
I can't do matlab...and have to plot the trajectory of alpha particles in rutherford scattering. I've made an attempt, but i know i've gone wrong somewhere. Could someone tell me how to fix it? I'd be SOOOO thankful...you've no idea!!
This is what i have so far, i've added it as an attachment as an m file.

I want it to look something like this:
http://www.kutl.kyushu-u.ac.jp/seminar/MicroWorld1_E/Part2_E/P25_E/Rutherford_S_E.jpg [Broken]

(and know the way i have it, there should only be one trajectory...i just want it to run! then i'll do it for other impact parameters too.

Thank you so much in advance!
 

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Answers and Replies

  • #2
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I haven't bothered to check the logic of your routine since, well, it's fugly. However, Matlab tells you precisely why your script won't run:

Code:
??? Attempted to access a_x(2); index out of bounds because numel(a_x)=1.
 
  • #3
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I haven't bothered to check the logic of your routine since, well, it's fugly. However, Matlab tells you precisely why your script won't run:

Code:
??? Attempted to access a_x(2); index out of bounds because numel(a_x)=1.
Is it that bad?? would i get any marks for it do you think?? I'm stressing, i don't have a clue whatto do!

Yeah, that's the error that came up,but i don't know how to fix it....do you???
 
  • #4
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The code doesn't look all that bad to me, but it definitely has problems. The variables have names that make it possible to guess what they should contain, and that's a plus, but you might have more variables than you need, which makes understanding the code more difficult.

Your problem is that you have an array a_x with 1 defined element, but in your for loop you are trying to read from a_x(2), a_x(3), etc., but there is no place in your code where you are giving values to these variables.

The first line in your for loop sets velocity_x(2) with the values in v_x(1) and a_x(2) and a_x(1). When do you assign a value to a_x(2)? Do you really need a variable v_x? Why not just use velocity_x instead?

Since you presumably wrote the for loop, you need to understand what it is doing, and you can do that by hand-simulating what the computer will do for an iteration or two at least. Start off with i = 1, and calculate the values that will be stored in velocity_x(2), position_x(2), velocity_y(2), and position_y(2). Doing this should increase your understanding of why you're getting the error you are getting.


A precondition for your for loop is that
 

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