I am trying to solve the following ODE:
function [eta, sol] = compressible_similarity_wo
global Gamm Ma Pr omega;
Gamm = 1.4;
Ma = 2;
Pr = 0.7;
omega=0.76;
global eta_max_ode;
eta_max_ode = 20;
opt = optimset('Display','off','TolFun',1E-20);
F = fsolve(@(F) eval_boundary(F),[0,0,0.4,1,0],opt);
[eta_ode, fg_ode] = solve_ode(F);
sol = [fg_ode];
eta = eta_ode;
end
function [eta_ode, fg_ode] = solve_ode(F)
global eta_max_ode
options = odeset('RelTol',1e-9,'AbsTol',1e-9);
[eta_ode, fg_ode] = ode45(@BLFunc,[0,eta_max_ode],F,options);
end
function [g] = eval_boundary(F)
% Get the solution to the ODE with inital condition F
[eta_ode, fg_ode] = solve_ode(F);
% Get the function values (for BCs) at the starting/end points
f_start = fg_ode(1,1); %f(0) = 0
df_start = fg_ode(1,2); %f'(0) = 0
df_end = fg_ode(end,2); %f'(inf) - 1 = 0
t_end = fg_ode(end,4); %T(inf) - 1 = 0
dt_start = fg_ode(1,5); %T'(0) = 0
% Evaluate the boundary function
g = [f_start
df_start
df_end - 1
t_end - 1
dt_start];
end
function [df] = BLFunc(f)
global Gamm Ma Pr omega;
df = zeros(5,1);
df(1) = f(2);
df(2) = f(3);
df(3) = -f(1)*f(3)/(f(4)^(omega-1))-(omega-1)*f(3)/f(4);
df(4) = f(5);
df(5) = -Pr*f(1)*f(5)/(f(4)^(omega-1)) - Pr*(Gamm - 1.0)*Ma*Ma*f(3)*f(3) - (omega-1)*f(5)/f(4);
end
but fsolve
returns the following problem
Error using BLFunc
Too many input arguments.
Error in odearguments (line 90)
f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.
Error in ode45 (line 115)
odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);
Error in solve_ode (line 5)
[eta_ode, fg_ode] = ode45(@BLFunc,[0,eta_max_ode],F,options);
Error in eval_boundary (line 3)
[eta_ode, fg_ode] = solve_ode(F);
Error in compressible_similarity_wo>@(F)eval_boundary(F) (line 15)
F = fsolve(@(F) eval_boundary(F),[0,0,0.4,1,0],opt);
Error in fsolve (line 230)
fuser = feval(funfcn{3},x,varargin{:});
Error in compressible_similarity_wo (line 15)
F = fsolve(@(F) eval_boundary(F),[0,0,0.4,1,0],opt);
Error in launch (line 3)
[eta, sol] = compressible_similarity_wo;
Caused by:
Failure in initial objective function evaluation. FSOLVE cannot continue.
Do you have an idea of what's going on?
I'll cite you the friendly manual page
The function
dydt = odefun(t,y)
, for a scalart
and a column vectory
, must return a column vectordydt
of data type single or double that corresponds tof(t,y)
.odefun
must accept both input arguments,t
andy
, even if one of the arguments is not used in the function.
That is, you simply need to change to
function [df] = BLFunc(t,f)
to get a result (no guarantee that it is THE result).