# Answer to Question #42269 in MatLAB | Mathematica | MathCAD | Maple for Majid

Question #42269

hi:

I wrote a code to solve an ODE using Runge-Kutta 4th order, but unfortunately it doesn't work properly.

i need your help please:

clc;

clear all;

% initial values

gamma = 1.4;

P1 = 101325; % Pa

T1 = 298; % K

Rho1 = 1.225; % kg/m3

tol = -(1e-6); % convergence criteria for Vtheta

Vtheta0 = -10; % fake value to initiate the while loop

delta_theta = 0.5; % angle marching

% inputs

M1 = input('Free stream Mach number=');

theta_c = input('cone angle in degree=');

theta_s = input('initial guess for shock angle in degree=');

while (Vtheta0 <= -tol) || (Vtheta0 >= tol)

% checking the correct input for beta

if (theta_s <= asind(1/M1))

theta_c = 0.0;

Mc = M1;

disp(' !!!!! theta_s > theta_s_max !!!!! ');

return;

end

% calculating the parametrs before shock

Mn1 = M1 * sind (theta_s);

Mu1 = M1 * cosd (theta_s);

P2 = P1 * (1 + (2 * gamma * (Mn1 ^ 2 - 1) / (gamma + 1)));

Rho2 = Rho1 * ((gamma + 1) * Mn1 ^ 2 / (2+((gamma - 1) * Mu1 ^ 2)));

T2 = T1 * P2 * Rho1 / (P1 * Rho2);

theta = atand (

I wrote a code to solve an ODE using Runge-Kutta 4th order, but unfortunately it doesn't work properly.

i need your help please:

clc;

clear all;

% initial values

gamma = 1.4;

P1 = 101325; % Pa

T1 = 298; % K

Rho1 = 1.225; % kg/m3

tol = -(1e-6); % convergence criteria for Vtheta

Vtheta0 = -10; % fake value to initiate the while loop

delta_theta = 0.5; % angle marching

% inputs

M1 = input('Free stream Mach number=');

theta_c = input('cone angle in degree=');

theta_s = input('initial guess for shock angle in degree=');

while (Vtheta0 <= -tol) || (Vtheta0 >= tol)

% checking the correct input for beta

if (theta_s <= asind(1/M1))

theta_c = 0.0;

Mc = M1;

disp(' !!!!! theta_s > theta_s_max !!!!! ');

return;

end

% calculating the parametrs before shock

Mn1 = M1 * sind (theta_s);

Mu1 = M1 * cosd (theta_s);

P2 = P1 * (1 + (2 * gamma * (Mn1 ^ 2 - 1) / (gamma + 1)));

Rho2 = Rho1 * ((gamma + 1) * Mn1 ^ 2 / (2+((gamma - 1) * Mu1 ^ 2)));

T2 = T1 * P2 * Rho1 / (P1 * Rho2);

theta = atand (

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