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# MATLAB中的點距離計算

假設空間中有三個點

分別是A(1,2,3) B(4,5,6) C(7,8,9)

請問要使用MATLAB中哪一個指令

計算AB與AC的距離

謝謝了!!

### 1 Answer

- Xman8668Lv 41 decade agoFavorite Answer
版大 您好:

您要求的是歐式空間的距離 可用 norm 求其距離 請您看以下範例:

程式碼:

clc;

clear all;

A = [1 2 3];

B = [4 5 6];

C = [7 8 9];

AB = B - A;

norm_AB = norm(AB)

AC = C - A;

norm_AC = norm(AC)

結果:

norm_AB =

5.1962

norm_AC =

10.3923

您也可用傳統求距離的方式: 兩個座標先相減後再平方開根號

來求解 可將 norm 代換成下列敘述:

length_AB = sqrt( sum(AB .* AB) )

length_AB = sqrt( sum(AB .^ 2) )

或

length_AC = sqrt( sum(AB .* AC) )

length_AC = sqrt( sum(AC .^ 2) )

結果是一樣的

length_AB =

5.1962

length_AC =

10.3923

2009-07-01 13:36:09 補充：

函式說明如下:

sum: 是將矩陣內的各元素相加

sqrt: 開根號