% Define the differential equation and boundary conditions
function dydt = ode9(t, y, p)
% Parameters
p1 = p(1); p2 = p(2); p3 = p(3);
% Differential equation
dydt = [
y(2);
y(3);
y(4);
y(5);
y(6);
y(7);
y(8);
y(9);
-p1*y(1) - p2*y(2) - p3*y(3)
];
end
% Boundary conditions
function bc = bc9(ya, yb, p)
% Parameters
p1 = p(1); p2 = p(2); p3 = p(3);
% Boundary conditions
bc = [
ya(1) - 0; % Velocity at x = 0
ya(2) - 1; % Velocity gradient at x = 0
ya(3) - 2; % Temperature at x = 0
ya(4) - 3; % Temperature gradient at x = 0
ya(5) - 4; % Concentration at x = 0
ya(6) - 5; % Concentration gradient at x = 0
yb(1) - 6; % Velocity at x = L
yb(2) - 7; % Velocity gradient at x = L
yb(3) - 8 % Temperature at x = L
];
end
% Shooting method
function [y, p] = shoot9(p0, tspan, y0)
% Initial guess for parameters
p = p0;
% Solve the differential equation
[t, y] = ode45(@(t,y) ode9(t, y, p), tspan, y0);
% Evaluate the boundary conditions
bc = bc9(y(1,:), y(end,:), p);
% Update the parameters using the Newton-Raphson method
while norm(bc) > 1e-6
J = jacobian(@(p) bc9(y(1,:), y(end,:), p), p);
dp = -J\bc;
p = p + dp;
[t, y] = ode45(@(t,y) ode9(t, y, p), tspan, y0);
bc = bc9(y(1,:), y(end,:), p);
end
end
% Example usage
tspan = [0 1];
y0 = [0 1 2 3 4 5 0 0 0];
p0 = [1 2 3];
[y, p] = shoot9(p0, tspan, y0);
```
the `ode9` function defines the 9th order differential equation, and the `bc9` function defines the 9 boundary conditions (velocity, temperature, and concentration at the start and end of the domain). The `shoot9` function implements the shooting method to solve the problem.
The shooting method involves guessing the initial parameter values (`p0`), solving the differential equation, evaluating the boundary conditions, and then updating the parameters using the Newton-Raphson method until the boundary conditions are satisfied within a specified tolerance.