MATLAB: Array and Matrix question

array matrix

How would I go about creating a 4×3 array/matrix and use some of its values to create another array/matrix that is 2×2? I have to use 'x=y(a:b:c,d:e:f)', where y is my initial 4×3 and x would be my 2×2, in order to create my second array. I keep getting 'Index exceeds matrix dimensions.' No matter what I try. This is what my code looks like:

y=[1 2 4;3 2 -1;2 4 5; -2 -1 10]

x=y(12:-8:4,10:-8:3)

Best Answer

Something like this, maybe? Note that you need to refer to nth row and nth column:

x=y(2:-1:1,3:-1:2)

Related Solutions

MATLAB: Finding the index of particular row in a matrix. Please explain what the code is doing

‘[x,y]=find(A(:,1)==B) returns x=3,2,4 and y=1,2,2 --- is this searching only in first column for 2.2? what does x and y mean in this case?’

Here, ‘x’ and ‘y’ are the row and column indices respectively. The line of code you quote in this line looks at the first column of ‘A’ for any values that match either of the values in ‘B’. Those values are referred to in the row and column indices respectively, specifically (3,1), (2,2), and (4,2).

‘[x,y]=find(A==B) returns x=3,3 and y=1,2 -- is this searching the entire row for [2.2,1.2]?’

Yes. It is matching the rows. The (x,y) indices are (3,1) and (3,2), so it is telling you that all of row 3 of ‘A’ matches ‘B’.

MATLAB: How to create a vector of this output

Try this:

[X,Y,Z] = ndgrid(-2:2);
Out = [Z(:),Y(:),X(:)]

producing:

Out =
    -2    -2    -2
    -2    -2    -1
    -2    -2     0
    -2    -2     1
    -2    -2     2
    -2    -1    -2
    -2    -1    -1
    -2    -1     0
    -2    -1     1
    -2    -1     2
    -2     0    -2
    -2     0    -1
    -2     0     0
    -2     0     1
    -2     0     2
         etc.

Best Answer

Related Solutions

MATLAB: Finding the index of particular row in a matrix. Please explain what the code is doing

MATLAB: How to create a vector of this output

Related Question