필터 지우기
필터 지우기

Solve multiple eigenvalue ODE problem with bvp4c

조회 수: 3 (최근 30일)
Anshuman Pal
Anshuman Pal 2021년 9월 2일
답변: darova 2021년 9월 5일
Hello,
I am following the bvp4c manual to solve an eigenvalue problem with two eigenvalues. I am getting an error `Error using vertcat: Dimensions of arrays being catenated are not consistent`. However, I think that this error might be due to some other inconsistency in my code. Could someone please help?
My code:
clear all
% parameters
global L Num
Num = 3000; % number of grid points. 3000 is plenty.
L = 1.0 ; % length of buckled portion of rod
tau0_init = 0; % 2 eigenvalues
deltaL_init = 0.1*L;
ss = linspace(0, L, Num);
solinit = bvpinit(ss, @mat4init, [tau0_init, deltaL_init]);
options = bvpset('Stats','on','RelTol',1e-5,'NMax',Num);
sol = bvp4c(@bvp_RHS, @bvp_BC, solinit, options);
fprintf('The eigenvalues are approximately %.2f.\n',sol.parameters)
figure
plot(sol.x, sol.y)
xlabel('s')
grid
legend(compose('$y_{%2d}$',1:11), 'Location','bestoutside', 'Interpreter','latex')
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function yinit = mat4init(x)
% initial guess for the solution
global L
yinit = [-sin(pi/L*x) % theta
-pi/L * cos(pi/L*x) % theta'
0.1 % x
0.1 % y
];
end
function dyds = bvp_RHS(x, y, tau0, deltaL)
% Total 4 variables.
% NB: eigenvalues tau0 and deltaL must be a function input even though if not present
% in any equation below.
global L
dyds = [ y(2)
-tau0*sin(y(1)) +(L-x)*cos(y(1))
cos(y(1))
sin(y(1))
];
end
function res = bvp_BC(yL, yR, tau0, deltaL)
% BCs at L and R boundaries, with constraint for eigenvalues tau0 and deltaL.
global L
res = [ yL(1)
yL(2)
yL(3)
yL(4)
yR(1)
yR(3)- 0.5*(L-deltaL)
];
end

답변 (1개)

darova
darova 2021년 9월 5일
Remove those spaces

카테고리

Help CenterFile Exchange에서 Boundary Value Problems에 대해 자세히 알아보기

태그

제품


릴리스

R2021a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by