MATLAB: How to choose the spcific intersection of two arry

intersectionMATLAB

how can I change the function so I could make it only return the intersection on the right, now it return the intersection point on the left.

Thank You !

The functioin I use:

function [maxSpeed,thrustDragVal] = maxSpeedThrustCalc(V, thrust, drag)

for difference = drag – thrust

[m,i] = min(abs(difference));

if (abs(difference) == m)

maxSpeed = V(i);

thrustDragVal = thrust(i);

end

Best Answer

function [maxSpeed,thrustDragVal] = maxSpeedThrustCalc(V, thrust, drag)
  i=find(abs(drag-thrust)<.1,1,'last');%not sure what tolerance you need
  maxSpeed = V(i);
  thrustDragVal = thrust(i);
end

Related Solutions

MATLAB: Indentify spcific point of matrixs

Hi Felix,

I see that the for loop condition is not correct. You can try the following

function [maxSpeed,thrustDragVal] = maxSpeedThrustCalc(V, thrust, drag)
for i = 1:length(thrust)
    difference = thrust(i) - drag(i);
    if abs(difference) <= 0.01 
        maxSpeed = V;
        thrustDragVal = thrust(i);
    end
end
end
% You mentioned that drag and thrust need to be known, but i am not sure why the output is set to maxSpeed
% You indicate the minimum difference, but why is the threshold placed as 0.01
% If both the above is same as what is said, you need to use the following code
difference = thrust - drag;
[m,i] = min(abs(difference)); % m is the minimum value and i is the index where minimum occurs
thrustVal = thrust(i);
dragVal = drag(i);

Hope this helps.

Regards,

Sriram

MATLAB: Error : Index exceeds the number of array elements (1).

Seems like some of your equations are wrong. I changed a few things so the code does not error. Array lengths need to match in equations and indexing cannot exceed or be below zero of the variable being referenced.

m_rocket = 95.6; %total mass of rocket (gm)
m_fuel = 15.6; %mass of fuel
f_thrust = 10.7; %force of thrust in N
a_rocket = 0.35; %sqm
c_drag = 0.06; %coefficient of drag
c_dragdown = 0.75; %c drag while falling down due to parachute
g = 9.81; %m/s^2
rho_air = 1.225; %kg/cubicm
drag = 0;
t(1) = 0; %time elapsed
h(1) = 0; %height m/s
v(1) = 0; %velocity m/s
a(1) = -g; %m/s
%% While loop
i=1;
h_check = h(1);
t_step = 0.1; %seconds
while h_check >= 0
    
    a(i+1) = ((m_rocket * g) - (0.5 * rho_air*v(i).^2 * c_drag * a_rocket)) / (m_rocket);
    
    v(i+1) = v(i) + (a(i)*t_step);
    
    h(i+1) = h(i) + (v(i)*t_step);
    
    t(i+1) = t(i) + t_step;
    
    h_check = h(i+1);
    
    i = i + 1;
    
    if (m_fuel(i - 1) - 5 * t_step) > 0 
        
         m_fuel(i) = m_fuel(i - 1) - 5 * t_step;
         
         f_thrust(i) = f_thrust(1);
         
    else
             m_fuel(i) = 0;
             
             f_thrust(i) = 0;
             
    end
    
    a_thrust(i) = (f_thrust(i) - drag(i-1)) / (m_rocket); %drag(i-1) 
    
    if m_fuel(i) == 0
        
        m_rocket = a(1);%changed m_rocket to not be an array
        
    else
        
        m_total(i) = (a_thrust(i - 1) + g);
        
    end
         drag(i) = -v(i-1) * abs(v(i-1)) * .0075;
         
         v(i) = v(i-1) + m_rocket * t_step;%m_rocket

         
         h(i) = h(i - 1) + v(i - 1) * t_step + (.5 * m_rocket * t_step .^2);%m_rocket
         
         a(i+1) = ((-m_rocket * g) + (0.5 * rho_air*v(i).^2 * c_drag * a_rocket)) / (m_rocket);
         
end
figure
plot (t,f_thrust)
title('Time vs Trust')
xlabel('Time')
ylabel('Thrust')
figure
plot (t,a(2:end))%acceleration is a longer array.
title('Time vs Acceleration')
xlabel('Time')
ylabel('Acceleration')
figure
plot (t,v)
title('Time vs Velocity')
xlabel('Time')
ylabel('Velocity')
figure
plot (t,h)
title('Time vs Altitude')
xlabel('Time')
ylabel('Altitude')

Best Answer

Related Solutions

MATLAB: Indentify spcific point of matrixs

MATLAB: Error : Index exceeds the number of array elements (1).

Related Question