a=rand(100,100);
tic
[b,pos]=sort(a(:,1));
aa=a(pos,:);
toc
tic
A=sortrows(a,1);
toc
det(aa-A)
前面的算法時間要短，效果是一樣的
Elapsed time is 0.000110 seconds.
Elapsed time is 0.000259 seconds.
ans =
0
用個小矩陣檢測下
a=magic(5);
tic
[b,pos]=sort(a(:,1));
aa=a(pos,:)
toc
tic
A=sortrows(a,1)
toc
det(aa-A)
a =
17 24 1 8 15
23 5 7 14 16
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
aa =
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
17 24 1 8 15
23 5 7 14 16
Elapsed time is 0.000133 seconds.
A =
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
17 24 1 8 15
23 5 7 14 16
Elapsed time is 0.000223 seconds.
ans =
0
tic
[b,pos]=sort(a(:,1));
aa=a(pos,:);
toc
tic
A=sortrows(a,1);
toc
det(aa-A)
前面的算法時間要短，效果是一樣的
Elapsed time is 0.000110 seconds.
Elapsed time is 0.000259 seconds.
ans =
0
用個小矩陣檢測下
a=magic(5);
tic
[b,pos]=sort(a(:,1));
aa=a(pos,:)
toc
tic
A=sortrows(a,1)
toc
det(aa-A)
a =
17 24 1 8 15
23 5 7 14 16
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
aa =
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
17 24 1 8 15
23 5 7 14 16
Elapsed time is 0.000133 seconds.
A =
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
17 24 1 8 15
23 5 7 14 16
Elapsed time is 0.000223 seconds.
ans =
0