create a matrice in a for loop

Hey guys, thanks in advance,

I have this moving radar, that detects targets in a specific area, identified by pixels(xtarget,ytarget).

In the end I have this distance_matrix, where rows are the distance to the target(R1-R2-Rd) and the columns are the position of the radar, since this radar is moving.

waypoints are the position of the radar, and it has, 400 positions(1:400 pixels). But the distance_matrix I have, saves the distances in 1 x 400, whic is correct, but if I have more than 1 target in each column(i), this code only saves one distance. I wanted that distance_matrix was a matrix that if column (i) had more that one distance to save, saved all the distances along that column. So imagine i=200, and in i there are 3 distances to save, so in i=200, distance_matrix should be 3x1 , and not 1x1 like I have, can you help me?

for i=1:numel(waypoints) % For each waypoint
    Y_transmitter = waypoints(i);

for xx=1:400
    for yy=1:400
        if AoI(xx,yy) ~= 0 % Target detection
            ....
                if status ==1 & Pt ==1 & Pr ==1  & Wi_Surv ~=0 & Wi_transmit ~=0  % SAR Passive detection
                ....
                R1=sqrt( (X_transmitter-X_target).^2 + (Y_transmitter-Y_target).^2); % Distance transmitter-target in meters
                R2=sqrt( (X_receiver-X_target).^2 + (Y_receiver-Y_target).^2); % Distance Receiver-target in meters
                Rd=sqrt( (X_receiverref-X_transmitter).^2 + (Y_receiverref-Y_transmitter).^2); % Distance Transmitter-Receiver in meters
                distance_matrix(:,i)=R1+R2-Rd;
                
                
                end
        end
    end
end
end

Answer 1

[Harshit Gupta]

Hi, I understand that you want to push more data in column (i) of your distance_matrix.

Try something like this:

distance_matrix(:,i)=[distance_matrix(:,i), new_value]

This will create a vector in each cell of your matrix

Hope this helps!

[Miguel Albuquerque]

This gets an error,

Unrecognized function or variable 'new_value'

.

[Harshit Gupta]

You to change 'new_value' with the value you want to push.

Like this:

distance_matrix(:,i)=[distance_matrix(:,i), R1+R2-Rd];

[Miguel Albuquerque]

Im doing this before the for loop

distance_matrix=zeros(1,length(waypoints)); % Define distance Signal matrix

and then:

distance_matrix(:,i)=[distance_matrix(:,i), R1+R2-Rd];
But I get this error
Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-2.

Error in SAR_Passive_Radar (line 260)
                        distance_matrix(:,i)=[distance_matrix(:,i), R1+R2-Rd];

[Stephen23]

distance_matrix=zeros(1,length(waypoints)); % defines a 1xN matrix.
distance_matrix(:,i) % refers to one column of a 1xN matrix, i.e. a 1x1 element.
[distance_matrix(:,i), R1+R2-Rd] % defines a 1x2 matrix.

How do you expect to fit two numbers into the space of one number?

distance_matrix=zeros(2,length(waypoints))
%                     ^

[Miguel Albuquerque]

Even if I define the first line as(2, length(waypoints)), it does the same error