Loop for bvp4c function with an unknown parameter
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I tried to solve sixth order differential equation using bvp4c with an unknown parameter “S” and one variable parameter “k”. I have written a subroutine as a bvp4c and a main function for “k”.
The main code is written as follows:
function [] = main()
kk=0.5 ;
for i=1:60
k=kk;
valuePresentstudy = Surfactant(k);
kk=kk+0.1;
end
end
The bvp4c subroutine is written as follows:
function valuePresentstudy = Surfactant(k)
options = bvpset('NMax',100000);
S=0.28;
solinit = bvpinit(linspace(0,1,100),[0.1 0 0 0 0 0],S);
sol = bvp4c(@(x,y)fourode(x,y,k),@(ya,yb)fourbc(ya,yb,k),solinit,options);
save hatimsol.mat sol
x = linspace(0,1);
y = deval(sol,x);
valuePresentstudy=y;
%
function dydx = fourode(x,y,S,k)
Pr=10;
dydx = [ y(2); y(3); y(4); -(k^4+(S/Pr)*k^2)*y(1)+(2*(k^2)+(S/Pr))*y(3); y(6); (k^2+S)*y(5)-y(1)];
%
function res = fourbc(ya,yb,S,k)
e=0;
res = [ ya(1); ya(2); ya(5); yb(1); yb(6)+e*k*yb(5); yb(5)-1; yb(6)];
The error is given as:
Error using Surfactant>@(x,y)fourode(x,y,k)
Too many input arguments.
Error in bvparguments (line 105)
testODE = ode(x1,y1,odeExtras{:});
Error in bvp4c (line 130)
bvparguments(solver_name,ode,bc,solinit,options,varargin);
Error in Surfactant (line 5)
sol = bvp4c(@(x,y)fourode(x,y,k),@(ya,yb)fourbc(ya,yb,k),solinit,options);
Error in MainPresentSurfactant (line 6)
valuePresentstudy = Surfactant(k);
Could you please tell me where my mistake is?
Thanks in advance for your help.
0 Comments
Accepted Answer
Torsten
on 7 Dec 2017
Maybe
sol = bvp4c(@(x,y,S)fourode(x,y,S,k),@(ya,yb,S)fourbc(ya,yb,S,k),solinit,options);
Otherwise pass k to fourode and fourbc as global.
Best wishes
Torsten.
More Answers (2)
Torsten
on 7 Dec 2017
function [] = main()
kk=0.5 ;
for i=1:60
k=kk;
valuePresentstudy = Surfactant(k);
kk=kk+0.1;
end
end
function valuePresentstudy = Surfactant(k)
global kk
kk = k;
options = bvpset('NMax',100000);
S=0.28;
solinit = bvpinit(linspace(0,1,100),[0.1 0 0 0 0 0],S);
sol = bvp4c(@fourode,@fourbc,solinit,options);
save hatimsol.mat sol
x = linspace(0,1);
y = deval(sol,x);
valuePresentstudy=y;
%
function dydx = fourode(x,y,S)
global kk
Pr=10;
dydx = [ y(2); y(3); y(4); -(kk^4+(S/Pr)*kk^2)*y(1)+(2*(kk^2)+(S/Pr))*y(3); y(6); (kk^2+S)*y(5)-y(1)];
%
function res = fourbc(ya,yb,S)
global kk
e=0;
res = [ ya(1); ya(2); ya(5); yb(1); yb(6)+e*kk*yb(5); yb(5)-1; yb(6)];
Best wishes
Torsten.
1 Comment
Tanya Sharma
on 7 Oct 2019
Hi Torsten, I am working on a similar kind of problem where S is unknown eigenvalue.
Can I evaluate eigenvalues S using bvp4c?
Akmaral Pussurmanova
on 6 May 2020
I don't know where is a mistake( Can you help me?
function dxdt = mat4ode(t,x,mu) % equation being solved
alfa = 0;
dxdt = [x(2)
-x(1)+0.1*(alfa*cos(2*t)*x(1)+x(1)^3)+mu*sin(2*t)+(1-pi^2)*sin(pi*t)+1-0.1*((sin(pi*t)+1)^3)-2*sin(2*t)];
end
%-------------------------------------------
function res = mat4bc(xa,xb,mu) % boundary conditions
res = [xa(1)-1
xb(1)-1
xa(2)-xb(2)];
end
%-------------------------------------------
function yinit = mat4init(t) % initial guess function
yinit = [sin(pi*t)+1
pi*cos(pi*t)
];
end
mu=2;
solinit = bvpinit(linspace(0,2,20),@mat4init,mu);
sol = bvp4c(@mat4ode, @mat4bc, solinit);
fprintf('Fourth eigenvalue is approximately %7.3f.\n',...
sol.parameters)
xint = linspace(0,2);
Sxint = deval(sol,xint);
plot(xint,Sxint)
axis([0 2 -4 4])
title('Eigenfunction of Mathieu''s Equation.')
xlabel('x')
ylabel('y')
legend('y','y''')
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