Euclidean distance of two vectors

Euclidean distance of two vector. I have the two image values G=[1x72] and G1 = [1x72]. I need to calculate the two image distance value.

[juit]

i have three points a(x1,y1) b(x2,y2) c(x3,y3) i have calculated euclidean distance d1 between a and b and euclidean distance d2 between b and c. if now i just want to travel through a path like from a to b and then b to c. can i add d1 and d2 to calculate total distance traveled by me???

Answer 1

[Jan]

Do you know the definition of the Euclidean distance?

G  = rand(1, 72);
G2 = rand(1, 72);
D  = sqrt(sum((G - G2) .^ 2));

A more efficient method, but this matters only for much larger vectors:

V = G - G2;
D = sqrt(V * V');

Or a Matlab command:

D = norm(G - G2);

A fast C-Mex function: http://www.mathworks.com/matlabcentral/fileexchange/29035-dnorm2

D = DNorm2(G - G2);

Searching in the documentation is faster than waiting for an answer in the forum. Therefore it is recommended to let Matlab search for the wanted keyword at first:

docsearch euclidean

[bala k]

thanks Jam simon..

[Joel]

Do you currently have this project with you? I want to compare two vector which totals 27 feature vectors for each image.

Your reply is greatly appreciated

[dali elite]

thanks a lot

[Jan]

@dali elite: Setting a flag is thought for calling the admin, such that they delete improper messages like spam or rudeness.

[Jared Willard]

I don't know about others but I am getting entirely different results when comparing

D  = sqrt(sum((G - G2) .^ 2));

and

D = norm(G - G2);

[James Tursa]

What are your G and G2 sizes? Are they real or complex?

[Jan]

@Jared: Please mention any details. What is the size and contents of your G and G2 variables? Check if your have redefined sqrt, sum or norm. Try:

format long g
clear variables
G  = rand(1, 72);
G2 = rand(1, 72);

D1 = sqrt(sum((G - G2) .^ 2))
V  = G - G2;
D2 = sqrt(V * V')
D3 = norm(G - G2)

Looks fine. And of course: The formulas are identical from a mathematical point of view. Then I'm sure you have overseen a detail in your comparison.

[Jan]

Concerning Rahul Ramkumar 's flag: "rude"

No, Rahul, this answer is not rude. I've posted 4 solutions and mentioned, that the OP can find an answer much faster by takine a look into the documentation. Many users are not familiatr with the docsearch command, although this is extremely useful and faster than waiting for an answer from the forum. It is worth to explain, that Matlab has some built-in tools to find solutions by your own.

[Rik]

This is about as rude as refering people to the FAQ: not very. It can sound a bit harsh, but it is valuable advice. You're getting free help from a stranger on the internet, that in itself is already friendly. You also need to account for the fact that for most people English is not their native language, and things may sound more rude to you than intended.

Because of these reasons I'm going to remove the flag. @Rahul Ramkumar, if you disagree, please post a comment with your reasoning. People on this forum are generally open to feedback and willing to edit their posts if good reasons are given.

[Jan]

Thanks, Rik. I've tried to elaborate my advice to search in the documentation before asking in the forum.

[Ben de Haas]

I've used Matlab for years and didn't know docsearch yet - thank you!

[Dalia]

what is the unit of D ?

[Rik]

@Dalia it inherits the unit of the inputs. If those inputs are not the same units, you will have to fix that first.

Answer 2

[Arash Azkia]

x = rand(n,1);

y = rand(n,1);

Distance = zeros(length(x) , length(y));

for i = 1:length(x)

for j = 1:length(y)

if i ~= j

Distance(i,j) = sqrt((x(i)-x(j))^2 + (y(i)-y(j))^2);

end

end

end