MATLAB: How to display Intersection of two graphs

graph

I am writing a code and plotting to set of equations against each other T_R and T_A. How can you make it so it disaplys the point where the two lines intersect?

I have attached the code and a picture of the graph thanks to anyone who can help

Best Answer

You need to create ‘T_A’ and ‘T_R’ as anonymous functions. After that, you can use fzero to calculate the intersection.

The Code —

S = 135.2; % ft^2
b = 35.5; % ft
C_D0 = 0.019;
e = 0.83;
W = 3000; % lbs
P_SSL = 195 * 0.85; %hp
rho_SSL = 0.002377;
AR = 9.321;
K = 1/(pi*e*AR);
hG = 1;
rho = 0.002377;
v = 40:10:750;
q = @(v) 0.5 * rho * v.^2;
C_L = @(v) W ./ (q(v) * S);
Dp = @(v) q(v) * S * C_D0;
Di = @(v) q(v) * S * K .* C_L(v).^2;
T_R = @(v) Dp(v) + Di(v);
P_A = P_SSL * (1.132 * (rho / rho_SSL) - 0.132);
T_A = @(v) (P_A * 550) ./ v;
v_int = fzero(@(v) T_R(v) - T_A(v), 300);
plot(v, T_R(v),    v, T_A(v))
hold on
plot(v_int, T_R(v_int), 'pg', 'MArkerFaceColor','g', 'MarkerSize',8)
hold off
grid
xlabel('v')
legend('T_R', 'T_A')
text(v_int+20, T_R(v_int)+20, sprintf('\\leftarrow (%.1f, %.1f)', v_int, T_R(v_int)), 'HorizontalAlignment','left', 'VerticalAlignment','middle')

Related Solutions

MATLAB: Help finding intersecting points

Try this:

W = 73000; %Airplane weight in lbs
Alt = 30000; %altitude given at 30000 feet
S = 950; %Area of the wing given in ft^2
AR = 5.92; %Aspect Ratio
Cd_o = 0.015; %coefficient of drag at 0 The value of 0.015 chosen for C0 _o is based on a generic value typical of streamlined, multiengine jet aircraft.
e = .9; %span efficiency factor
k_3 = 1/(pi*e*AR);
k_2 = 0;
k_1 = (1/3)*k_3;
K = k_1+k_2+k_3; %I'm not sure
 
 
V = linspace(400, 2400, 1000); %Velocity feet per second
rho = 8.9068*10^(-4); %Density at 30000 ft
C_l = ((2*W)./(rho*V.^2*S)); %coefficient of lift
C_d = Cd_o+K*(C_l).^(2); %Coefficient of drag
T_r = (1/2*rho.*V.^2.*S.*C_d); %Thrust given in lbs
D = T_r; %Thrust = Drag page 205 last paragragh
P_r = V.*T_r;
T_a = 13850*2; %lb/f
P_a = V.*T_a;
intx_V  = interp1(P_r-P_a, V, 0);
intx_Pr = interp1(V, P_r, intx_V);
 
figure
hold on
plot(V, P_r)
plot(V, P_a)
plot(intx_V, intx_Pr, 'sr')
hold off
text(intx_V,intx_Pr, sprintf('(%6.1f, %9.1f) \\rightarrow', intx_V,intx_Pr), 'HorizontalAlignment','right', 'VerticalAlignment','middle')

producing:

Best Answer

Related Solutions

MATLAB: Help finding intersecting points

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