Question

I have matrix

A=magic(4)*10

and matrix

B=[6 6 2 6;  1 1 2 1; 7 7 2 1; 3 3 -1 3 ]

I want to get values of A depending on values in B. For example:

A=
160 20  30  130
50  110 100 80
90  70  60  120
40  140 150 10

B=
6   6   2   6
6   6   2   2
2   6   2   6
6   2   -1  2

I want to start at A(1,1) (value=160). Then, If the corresponding value on B, B(1,1) = 6, I want to get the element that is on the right, A(1,2), and if B(1,1) = 2, I want to get value that is below, A(2,1). Finally, if the value is -1, I do not want to proceed. In the end I want to get result like this:

result=
160
20
30
100
60

Can anyone help me please?

Answer 1

Try the following code:

% Inizialize matices
A=magic(4)*10;
B=[6 6 2 6;  1 1 2 1; 7 7 2 1; 3 3 -1 3 ];

% Inizialize internal variables
contin=1;
row=1;
column=1;
result=[];

while contin==1
    %append value
    result=[result A(row, column)];
    if B(row, column)==6
        column=column+1; %go to the right
    elseif B(row, column)==2
        row=row+1; %go down
    elseif B(row, column)==-1
        contin=0; %break
        result(end)=[]; %delete last value 
    end
end

result