how to find out distance between two points.

I have 8*2 matrix of numbers like

2 1

3 2

4 3

5 2

6 2

7 3

8 3

9 8

and another matrix of coordinates for these numbers like

1 19.75303200 0.43557600 2.65388300

2 0.77047300 0.06860900 2.48736300

3 1.50647300 19.88576300 3.80387500

4 2.93388400 19.40857700 3.52875700

5 1.29467400 0.79392000 1.85730000

6 0.70911200 19.12320300 1.93804200

7 1.57899700 0.85145000 4.31768200

8 0.80276600 18.88574500 4.70559200

9 0.74693100 17.90090500 4.22987600

now I have to find out the distace between points from column 1 to 2 of first marix using the coordinates from 2nd matrix. how can i do it?

[Luna]

if it is a solution please accept my answer below :)

Answer 1

[Luna]

Here you can use this:

NodeNumbersMatrix = [...
    2  1
    3  2
    4  3
    5  2
    6  2
    7  3
    8  3
    9  8 ...
    ];
CoordinatesMatrix = [...
    1              19.75303200      0.43557600       2.65388300
    2              0.77047300       0.06860900       2.48736300
    3              1.50647300       19.88576300      3.80387500
    4              2.93388400       19.40857700      3.52875700
    5             1.29467400       0.79392000       1.85730000
    6              0.70911200       19.12320300      1.93804200
    7              1.57899700       0.85145000       4.31768200
    8              0.80276600       18.88574500       4.70559200
    9              0.74693100       17.90090500       4.2298760 ...
    ];

distance_array = nan(size(NodeNumbersMatrix,1),1); % preallocate

for i = 1:size(NodeNumbersMatrix,1)   
    points_to_look_between = NodeNumbersMatrix(i,:);    
    two_vectors_of_points = CoordinatesMatrix(points_to_look_between,2:end);    
    distance_of_two_vectors = sqrt(sum((two_vectors_of_points(1,:) - two_vectors_of_points(2,:)).^2));
    distance_array(i) = distance_of_two_vectors;
end

%% OR 
% shorter way for loop

for i = 1:size(NodeNumbersMatrix,1)
    two_vectors_of_points = CoordinatesMatrix( NodeNumbersMatrix(i,:),2:end);    
    distance_array(i) = sqrt(sum((two_vectors_of_points(1,:) - two_vectors_of_points(2,:)).^2));  
end