How to iterate through a column vector elements one by one?

Hello Guys! I am new to matlab and working on a project. I want to iterarte through a column vector and retrive element of column one by one into another variable. That is, I want to retrive first element from a matrix of 1382x1 and then compute it and then the next element and so on. Kindly Help me out. I knw it would be using for loop but I cant find a solution.

[Torsten]

I want to retrive first element from a matrix of 1382x1 and then compute it and then the next element and so on.

?

[Prahlad Roy]

I am making a project on fall detection using mobile acceleration sensors whose algorithm is to be made on matlab platform. Accelerometers in mobile devices have three parameters, accel_x, accel_y,accel_z. So to compute the final acceleration we do: Acc = sqrt(accel_x^2+accel_y^2+accel_z^2). So I when I record the acceleration from mobile phone sensors I got a column matrix of 1382x1 for each parameter x,y&z. So is there any way to calculate the final acceleration (Acc) from those columns? and the final result could be a single value instead of 1382 values? Hope uunderstand.

[Voss]

Acc = sqrt(accel_x.^2+accel_y.^2+accel_z.^2)

or

accel = [accel_x accel_y accel_z];
Acc = sqrt(sum(accel.^2,2))

or

Acc = sqrt(sum([accel_x accel_y accel_z].^2,2))

So how do you want to get a single value from those 1382 Acc values?

[Prahlad Roy]

>> m=mobiledev

%m = 
%Current Sensor Values:
                %Acceleration: [0x3 double] (Waiting for data)
             %AngularVelocity: [0x3 double] (Waiting for data)
             
[a,t]= accellog(m); %retriving aceeleration data fom mobile
[b,t]= angullog(m): %retriving angular velocity data fom mobile

LFT_accel=0.3;               % Lower Fall Threshold  0.3g (0.3*9.8m^2/s)
UFT_accel=2.8;               % Upper Fall Threshold  2.8g
UFT_ang=200;                 % Upper Fall Threshold  200 degree/s


% receive/and judge    six data are processed in one loop
memLen=10;                       % The length of motion data memory
motionData=zeros(6,memLen);      % Motion data memery
memPoint=1;                      % Current processing time point
lastPoint=0;                     % The last time point before current one


while(memPoint~=0)                            % with a period of fall duration
    
accel_x = a(1,1);
accel_y = a(1,2);
accel_z = a(1,3);

    ang_x = b(1,1);
    ang_y = b(1,2);
    ang_z = b(1,3);
    
motionData(1,memPoint)=accel_x;     % Acceleration on axis x
motionData(2,memPoint)=accel_y;     % Acceleration on axis y
motionData(3,memPoint)=accel_z;     % Acceleration on axis z
motionData(4,memPoint)=ang_x;       % Angular rate on axis x
motionData(5,memPoint)=ang_y;       % Angular rate on axis y
motionData(6,memPoint)=ang_z;       % Angular rate on axis z

Acc=sqrt(accel_x^2+accel_y^2+accel_z^2);
if (Acc<=LFT_accel)
lastPoint=mod(memPoint-9,memLen);

    Acc=sqrt(motionData(1,lastPoint)^2+motionData(2,lastPoint)^2+motionData(3,lastPoint)^2);

Angular=sqrt(motionData(4,lastPoint)^2+motionData(5,lastPoint)^2+motionData(6,lastPoint)^2);

if (Acc>=UFT_accel&& Angular>=UFT_ang)
        disp('A Fall Has Happened!');
end
else
    disp('No Fall');
end

memPoint=mod(memPoint+1,memLen);
end 

So in this code I can calculate the Acc and Angular for first element of each column.. I want to calculate it for each next values....

accel_x = a(1,1);
accel_y = a(1,2);
accel_z = a(1,3);

How can I do that? Please help!

Answer 1

[Voss]

v = rand(1382,1); % 1382x1 column vector

N = numel(v);
final_result = zeros(N,1); % "another variable", the same size as v

for ii = 1:N
    
    % retrieve ii-th element of v:
    current_value = v(ii);
    
    % do something with current_value to get a result:
    current_result = current_value^2;
    
    % store the result in the final_result vector:
    final_result(ii) = current_result;
    
end

Or, without the use of the temporary variables current_value and current_result:

for ii = 1:N
    
    % compute the result for the ii-th element of v, and 
    % store it in the final_result vector:
    final_result(ii) = v(ii)^2;
    
end

However, depending on what your computation entails, you may be able to avoid the loop entirely. For example, the above can be written as:

final_result = v.^2;