Error: starting_stepsize

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Buey Cande
Buey Cande on 17 Dec 2021
Answered: VBBV on 18 Feb 2025
I get an error and my code is at below
error: starting_stepsize: operator /: nonconformant arguments (op1 is 1x1, op2 is 1x2)
error: called from
starting_stepsize at line 55 column 8
ode45 at line 192 column 25
kpri at line 17 column 8
My code is at below
Fao=5;
ep=0;
d=[0.01:2];
kprime=3.*(3./(60.*d).^2).*(((60.*d).*coth(60.*d.*pi./180))-1);
alpha0=0.8*10^-4./d;
Cao=0.207;
DEs=@(W,xy) [(((Cao.*(1-xy(1)).*xy(2)).^2/Fao).*kprime); (-alpha0./(2.*xy(2)))];
xy=[0,1];
Wspan=linspace(0,100,5);
[W,xy] = ode45(DEs,Wspan,xy);
figure(1)
plot(W, xy)
grid
legend('x(W)', 'y(W)')

Answers (1)

VBBV
VBBV on 18 Feb 2025
@Buey Cande See the following changes to your code
Fao=1.5;
%ep=0;
d=[0.1:0.25:1];
kprime=3.*(3./(60.*d).^2).*(((60.*d).*coth(60.*d.*pi./180))-1);
alpha0=0.8*10^-4./d;
Cao=0.567;
y0=[0 1];
Wspan=[0 5];
figure(1)
hold on
for k = 1:numel(kprime)
[W,y] = ode45(@(W,y) DEs(Cao,Fao,kprime(k),alpha0(k),W,y),Wspan,y0);
plot(W, y,'linewidth',2)
end
function dey = DEs(Cao,Fao,kprime,alpha0,W,y)
dey = zeros(2,1);
dey(1) = ((Cao.*(1-y(1)).*y(2)).^2)/Fao.*kprime;
dey(2) = (-alpha0./(2.*y(2)));
end
axis([0 5 0 0.95])
grid
%legend('x(W)', 'y(W))

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