Doubt in solving ODE45

I am trying to solve a differential equation for parameter 'dis' for infinite length of beam which is function of time and space in ode45.I am doubtful about how to consider infinite 'L' in the analysis, as my time is dependent upon v (velocity) and L (length).

I tried solving ode45 as usual taking arbitary L=20 but want to plot 'dis' wrt to space.I need help in plotting.My code has been attached herein.

[Jan]

The code is not visible yet.

[Susmita Panda]

Sir,please check my code.

Answer 1

[Star Strider]

It seems that ‘dis’ does not appear anywhere.

L=20;
v=20;%v (m/sec)
T=L/v;
tspan_1=[0:0.001:T];%time range 
y0_1=[0;0];%initial conditions 
[t1,y1]=ode45(@diffeqn11,tspan_1,y0_1);

figure()
plot(t1, y1(:,1), 'r', 'LineWidth',2)
grid
xlabel('t_1')
ylabel('y_1')

function f= diffeqn11(t,y)
A=250;B=20;C=10;j=1;L=20;v=20;a=0.5;%a=x/L
f=zeros(2,1);
f(1)=y(2);
f(2)=(A*sin(j*pi*v*t/L)-B*y(2)-C*y(1))*sin(j*pi*a);%Dimensional
end

EDIT — (20 Sep 2021 at 19:24)

If you have ‘y’ as a function of space and time, this is a partial differential equation.

Express appropriately as a function of both space and time, and then solve it with the pdepe function, or the partial Differential Equation Toolbox functions.

.

Answer 2

[Susmita Panda]

Y1 is my "dis" parameter which i need to plot wrt to space