matrix question

Q =

    10    20    30    40    50    60    70
     8     9    10    11    12    13    14
    33    30    27    24    21    18    15
    28    35    42    49    56    63    70
    36    45    54    63    72    81    90
    -1    -2    -3    -4    -5    -6    -7
    64    69    74    79    84    89    94

required to find:

T=

64 79 94

28 49 70

10 40 70

I used syntax Q([7:21:49; 4:21:49; 16:6:49;])

but it doesn't work. I can only get

64 79 94

28 49 70

using Q([7:21:49; 4:21:49]) and it doesn't accept Q([7:21:49; 4:21:49; 16:6:49;])... any ideas?

[Dwyane Wade]

I have a new answer : Q(1:3:7, [1;4;7]) which yields to:

10 40 70

28 49 70

64 79 94

now how do I flip this upside down? help me pls

[Paulo Silva]

The flipud function does that but you can easily avoid using it, see my answer below.

[Dwyane Wade]

I got it now guys!

flipud(Q(1:3:7, [1;4;7]))

Thanks for the help anyway!

Answer 1

[Paulo Silva]

Q =[10    20    30    40    50    60    70
     8     9    10    11    12    13    14
    33    30    27    24    21    18    15
    28    35    42    49    56    63    70
    36    45    54    63    72    81    90
    -1    -2    -3    -4    -5    -6    -7
    64    69    74    79    84    89    94]
Q(7:-3:1,1:3:7)

[Dwyane Wade]

Thank you sir but I've found a much efficient way of doing this :

flipud(Q(1:3:7, [1;4;7]))

I learned that from you! Thank you! :)

[Paulo Silva]

sorry but that's not efficient at all, you are using a function without needing it.

[Dwyane Wade]

its ok we are allowed to use it sir. thank you for the help!