Borrar filtros
Borrar filtros

substituting function variable in function handle

14 visualizaciones (últimos 30 días)
Bathala Teja
Bathala Teja el 14 de Sept. de 2021
Editada: Jaynik el 3 de Abr. de 2024
i want to substitute y(5) in place of theta and poceed for the ode calculations.
Here is my script
syms theta
A0 = cos(theta).*[1 5 6; 2 9 3; 1 4 5];
A =[A0 zeros(3, 2);
zeros(2, 3) [1 0; 0 1]]
B = tan(2*theta).*[8 5 1 0 0; 1 1 6 0 0; 2 4 7 0 0; 0 0 0 0 0; 0 0 0 0 0]
C = (cos(2*theta)+2).*[8 5 1; 0 1 6; 2 4 7];
myfun = @(t,y)scriptname(t,y,A,B,C);
% dummy values for tspan and y0
tspan = [0 1];
y0 = zeros(1, 5);
An = matlabFunction(subs(A, y(5)))
Bn = matlabFunction(subs(B, y(5)))
Cn = matlabFunction(subs(C, y(5)))
sol = ode45(myfun,tspan,y0);
h = figure;
plot(sol.x,sol.y(i,:));
function dydt = scriptname(t,y,An,Bn,Cn)
inertia = 0.05;
Wr = 2*pi*50;
p =2;
% Cn = double(subs(C,y(5)))
for i=1:3
I(i,1)=y(i);
end
I
Te = 1/2*p*I'*Cn*I
if t<0.75
Tl=0;
else
Tl=7.31;
end
V = [1.4142*400/sqrt(3)*cos(Wr*t);
1.4142*400/sqrt(3)*cos(Wr*t+2.*pi/3.);
1.4142*400/sqrt(3)*cos(Wr*t-2.*pi/3.);
(Te-Tl)/inertia;
y(4)]
% An = double(subs(A,y(5)))
% Bn = double(subs(B,y(5)))
dydt = An\V-(Bn*y);
end
It is showing the error of "unrecognized function or variable y".
  3 comentarios
Bathala Teja
Bathala Teja el 14 de Sept. de 2021
sir can you please rewite my script with your changes?
iam really confused sir please help me out
Bathala Teja
Bathala Teja el 14 de Sept. de 2021
hello
anything edited??

Iniciar sesión para comentar.

Respuestas (1)

Jaynik
Jaynik el 2 de Abr. de 2024
Editada: Jaynik el 3 de Abr. de 2024
Hi Bathala,
The error you are encountering occurs because "y" is not defined in the scope where you are trying to substitute "y(5)" for "theta" in matrices "A", "B", and "C". To fix this issue, "y" must first be declared as a symbolic variable. that represents a vector, and then perform the substitution.
You can refer to the following code:
syms theta
syms y [5 1]
A0 = cos(theta).*[1 5 6; 2 9 3; 1 4 5];
A =[A0 zeros(3, 2); zeros(2, 3) [1 0; 0 1]];
B = tan(2*theta).*[8 5 1 0 0; 1 1 6 0 0; 2 4 7 0 0; 0 0 0 0 0; 0 0 0 0 0];
C = (cos(2*theta)+2).*[8 5 1; 0 1 6; 2 4 7];
% Substitute theta with y(5) in A, B, C
A_sub = subs(A, theta, y(5));
B_sub = subs(B, theta, y(5));
C_sub = subs(C, theta, y(5));
% Convert the substituted expressions to MATLAB functions
An = matlabFunction(A_sub, 'Vars', {y});
Bn = matlabFunction(B_sub, 'Vars', {y});
Cn = matlabFunction(C_sub, 'Vars', {y});
function dydt = scriptname(t, y, An, Bn, Cn)
inertia = 0.05;
Wr = 2*pi*50;
p = 2
% Using the An, Bn, and Cn functions with the current state vector y
A_current = An(y);
B_current = Bn(y);
C_current = Cn(y);
I = y(1:3);
Te = 1/2 * p * I' * C_current * I;
if t < 0.75
Tl = 0;
else
Tl = 7.31;
end
V = [1.4142*400/sqrt(3)*cos(Wr*t);
1.4142*400/sqrt(3)*cos(Wr*t+2*pi/3);
1.4142*400/sqrt(3)*cos(Wr*t-2*pi/3);
(Te - Tl) / inertia;
y(4)];
dydt = A_current \ V - (B_current * y);
end
You can refer the following documentation to read more about these functions:
Hope this helps!

Productos


Versión

R2021a

Community Treasure Hunt

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

Start Hunting!

Translated by