3D Logarithmic Spiral Code

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Aadil 2013-3-27

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https://ww2.mathworks.cn/matlabcentral/answers/68872-3d-logarithmic-spiral-code

Hello,

I need to generate a 3D Logarithmic Spiral !

Can anybody help me with the code.

Thanks!!!!!!!!!

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Aadil 2013-3-27

Hi Cedric,

Thanks for the response. I have generated the spiral but it is an Archimedian Type. I need a logarithmic 3d spiral instead. Please help if you can.

Cedric 2013-3-27

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Well, you've seen that already I guess http://en.wikipedia.org/wiki/Logarithmic_spiral

so you have a formula for x(t) and y(t), and you could generate a formula for z(t) as t/100 for example.

Now you want to create a vector of all times that you want to consider, e.g.

>> t = 0:0.1:100 ;

and compute x, y, and z from there. Play a bit with a smaller vector t and see what you can do, keeping in mind that multiplying vectors element by element requires a dotted operator..

 >> t = 1:4
 t =
     1     2     3     4
 >> exp(t)
 ans =
    2.7183    7.3891   20.0855   54.5982
 >> sin(t)
 ans =
    0.8415    0.9093    0.1411   -0.7568
 >> exp(t) * sin(t)     % Wrong way to perform element-wise multiplication..
 Error using  * 
 Inner matrix dimensions must agree.
 >> exp(t) .* sin(t)    % Correct way; each element of the output is the 
                        % product of corresponding elements of the inputs.
 ans =
    2.2874    6.7188    2.8345  -41.3200