octave:7> A
A =
1 2
3 4
5 6
octave:8> B
B =
11 12
13 14
15 16
octave:9> C
C =
1 1
2 2
octave:10> A * C
ans =
5 5
11 11
17 17
- ".": element wise operation
octave:11> A .* B
ans =
11 24
39 56
75 96
octave:12> A .^2
ans =
1 4
9 16
25 36
octave:13> A'
ans =
1 3 5
2 4 6
octave:28> a = [1 15 2 0.5]
a =
1.00000 15.00000 2.00000 0.50000
octave:29> val = max(a)
val = 15
octave:30> [val, ind] = max(a)
val = 15
ind = 2
octave:31> A
A =
1 2
3 4
5 6
octave:32> max(A)
ans =
5 6
--------------------------------------------
octave:38> temp1 = [1 10; 2 11; 3 12];
octave:39> temp2 = [10 1; 20 21; 30 3];
octave:40> max(temp1, temp2)
ans =
10 10
20 21
30 12
--------------------------------------------
octave:42> A
A =
8 1 6
3 5 7
4 9 2
octave:43> max(A, [], 1)
ans =
8 9 7
octave:44> max(A, [], 2)
ans =
8
7
9
---------------------- % to find the max value in the matrix
octave:45> max(max(A))
ans = 9
octave:46> max(A(:))
ans = 9
octave:34> A = magic(3)
A =
8 1 6
3 5 7
4 9 2
octave:35> [r, c] = find(A > 7)
r =
1
3
c =
1
2
octave:36> sum(a)
ans = 18.500
octave:37> prod(a)
ans = 15
-------------------------------------% to sum up the diagonal element
octave:47> A = magic(9)
A =
47 58 69 80 1 12 23 34 45
57 68 79 9 11 22 33 44 46
67 78 8 10 21 32 43 54 56
77 7 18 20 31 42 53 55 66
6 17 19 30 41 52 63 65 76
16 27 29 40 51 62 64 75 5
26 28 39 50 61 72 74 4 15
36 38 49 60 71 73 3 14 25
37 48 59 70 81 2 13 24 35
octave:48> sum(A, 1)
ans =
369 369 369 369 369 369 369 369 369
octave:49> sum(A, 2)
ans =
369
369
369
369
369
369
369
369
369
octave:50> A .*eye(9)
ans =
47 0 0 0 0 0 0 0 0
0 68 0 0 0 0 0 0 0
0 0 8 0 0 0 0 0 0
0 0 0 20 0 0 0 0 0
0 0 0 0 41 0 0 0 0
0 0 0 0 0 62 0 0 0
0 0 0 0 0 0 74 0 0
0 0 0 0 0 0 0 14 0
0 0 0 0 0 0 0 0 35
octave:51> sum(A.*eye(9))
ans =
47 68 8 20 41 62 74 14 35
octave:52> sum(sum(A.*eye(9)))
ans = 369
-----------------------------------------------%to sum up the opposite diagonal
octave:53> flipud(eye(9))
ans =
Permutation Matrix
0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 1 0
0 0 0 0 0 0 1 0 0
0 0 0 0 0 1 0 0 0
0 0 0 0 1 0 0 0 0
0 0 0 1 0 0 0 0 0
0 0 1 0 0 0 0 0 0
0 1 0 0 0 0 0 0 0
1 0 0 0 0 0 0 0 0
octave:54> sum(sum(A .* flipud(eye(9))))
ans = 369
octave:55> A = magic(3)
A =
8 1 6
3 5 7
4 9 2
octave:56> pinv(A)
ans =
0.147222 -0.144444 0.063889
-0.061111 0.022222 0.105556
-0.019444 0.188889 -0.102778
octave:57> A * pinv(A)
ans =
1.0000e+00 -1.1713e-14 6.3283e-15
4.1633e-17 1.0000e+00 -1.1102e-16
-5.9119e-15 1.2490e-14 1.0000e+00
