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

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Sanaz Kb am 25 Feb. 2018
Kommentiert: Rik am 9 Mär. 2018
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:
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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### Antworten (1)

Rik am 25 Feb. 2018
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);
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Rik am 9 Mär. 2018
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);

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