Computing Euclidean distance between 2 points

Question

0 个投票

I found a code computing Euclidean distance as

diff = q - p;
dist = sqrt(diff * diff');

is there any difference from the standard Euclidean distance formula, why transpose is taken?

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Answer 1

Rik 2022-5-3

编辑：Rik 2022-5-3

1 个投票

By doing a matrix multiplication on a vector, you implicitly take the sum over all elements.

Note that this will only work if both p and q are row vectors.

q=rand(1,5);p=rand(1,5);
diff=q-p;
diff * diff'  ,  sum(diff .* diff)
ans = 0.6624
ans = 0.6624

Answer 2

Bruno Luong 2022-5-3

编辑：Bruno Luong 2022-5-3

1 个投票

For a row vector d

% sum(d.^2)

is equal to

% d*d'

Example

d=randi(10,1,3)
d = 1×3
     9     6     5
sum(d.^2)
ans = 142
d*d'
ans = 142