how to calculate the distances between points coordinates and the arbitrary reference point using loops?

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Sanaz Kb 2018-2-25

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https://ww2.mathworks.cn/matlabcentral/answers/384700-how-to-calculate-the-distances-between-points-coordinates-and-the-arbitrary-reference-point-using-lo

评论： Rik 2018-3-9

This solution is solved before within a little change, They have calculated the distances between pairwise coordinate. as you can see inside the link below:

https://uk.mathworks.com/matlabcentral/answers/276608-how-to-calculate-the-distances-between-pairwise-coordinates-using-loops-please-help-me

But in my question the X and Y have points inside which are increase sequentially. For example:

Let us consider:

X = [0 2 4 6;  0 2 4 6;  0 2 4 6]; % and 
Y = [0 0 0 0;  2 2 2 2;  4 4 4 4;  6 6 6 6];

all of the points inside X and Y are due to the geometry of my model configuration. Let consider a reference point which is inside the model.I need to find the distance between all points and reference point. I know that I should use a loop for the sequential changes but I don't know how?

I should note that the configuration may be changed.

Thank you

Sanaz

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回答（1 个）

Rik 2018-2-25

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/384700-how-to-calculate-the-distances-between-points-coordinates-and-the-arbitrary-reference-point-using-lo#answer_306981

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If X and Y contain the coordinates of your sample points, then the code below will give you the Euclidean distance between the fixed point and the sample points.

F_x=3;F_y=3;%coordinates of the fixed point
E_distance=sqrt((X-F_x).^2+(Y-F_y).^2);

I don't really see the connection to the question you linked to, so please leave a comment if this isn't what you mean.

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Sanaz Kb 2018-2-26

编辑：Sanaz Kb 2018-3-1

在 MATLAB Online 中打开

Dear all thank you in advance for your useful answers. Now, I have found my solution by myself. In below I put the code and I hope it would be helpful for the users.

clc clear all format long

 pos_x = 4;  % number of the position in x coordinate
 pos_y = 3;    % number of the position in y coordinate
 u = []
 v = []
 for i = 1:pos_x
     u = [u, 2*(i-1)];
     X = repmat(u,pos_y,1).';
     v = [v,2*(i-1)];
     Y = repmat(v,pos_y,1).';
 end
n = size(X,2);
m = size(Y,2);
D = zeros(n,m);
xo = 0.5; % reference point x coordiante
yo = 0.5; % reference point y coordinate
for ii = 1:n
    for jj = 1:m
       D(ii,jj) = sum(sqrt((xo-X(ii)).^2 + (yo-Y(jj)).^2));
    end
end

Rik 2018-3-9

在 MATLAB Online 中打开

You can optimize your code like this:

pos_x = 4;  % number of the position in x coordinate
pos_y = 3;    % number of the position in y coordinate
u = [];
v = [];
for i = 1:pos_x
    u = [u, 2*(i-1)];
    X = repmat(u,pos_y,1).';
    v = [v,2*(i-1)];
    Y = repmat(v,pos_y,1).';
end
n = size(X,2);
m = size(Y,2);
D = zeros(n,m);
xo = 0.5; % reference point x coordiante
yo = 0.5; % reference point y coordinate
x_elem=X(1:n);
y_elem=Y(1:m);
[X2,Y2]=meshgrid(x_elem,y_elem);
D=hypot(xo-X2,yo-Y2);

But are you sure you don't mean something like the code below? Because your code results in a D that is not described by pos_x or pos_y.

pos_x = 4; % number of the position in x coordinate
pos_y = 3; % number of the position in y coordinate
xo = 0.5;  % reference point x coordiante
yo = 0.5;  % reference point y coordinate
u=0:2:(2*(pos_x-1));
v=0:2:(2*(pos_y-1));
[X,Y]=meshgrid(u,v);
D=hypot(xo-X,yo-Y);