How to relate or understand this code with math formula?

2013 3 12
1 个回答
回答已采纳
2 次查看（30 天）

0 个投票

Having a matrix (Vertices) with vertices points of a skeleton line (all points x,y). And two (column) vector matrices Na and Nb which describe the logical indexes of the matrix Vertices... can someone explain me better (the actual mathematics) of these pieces of code? Well, actually are the same:
% Correct for sampling differences
Ta = -sqrt(sum((Vertices-Vertices(Na,:)).^2,2));
Tb = sqrt(sum((Vertices-Vertices(Nb,:)).^2,2));

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Mauricio Escobar
Mauricio Escobar 2013-3-13
编辑：Mauricio Escobar 2013-3-13
So is the distance between two points: sqrt[ (x - y)^2 +(x'- y')^2 ]
I still have one doubt...
The part after squaring: ,2 ));
Inside the sum(().^2 , 2)
What does it do?
Is it to sum two columns?

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Doug Hull
Doug Hull 2013-3-12

0 个投票

It looks like it is taking the delta between every vertex in the list and a specific vertex (a or b).
It is then squaring those two scalars, deltaX and deltaY
It is then summing them
Then taking the square root of the is. Is is negating the first one.
Essentially, it is finding the distance between a point and a list of points.

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Mauricio Escobar
Mauricio Escobar 2013-3-12
Thanks Doug Hull (excellent videos on GUI BTW! Thanks for those, a lot!)
When you say delta, what do you mean? The difference, right?
Mauricio Escobar
Mauricio Escobar 2013-3-13
编辑：Mauricio Escobar 2013-3-13
I still have one doubt...
The part after squaring: ,2 ));
Inside the sum(().^2 , 2)
What does it do?
Is it to sum two columns?
Walter Roberson
Walter Roberson 2013-3-13
sum along the second dimension (i.e., along the rows). sum() defaults to summing down the columns.

请先登录，再进行评论。

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Graph and Network Algorithms 的更多信息

产品

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by