I’m a new Julia user but matlab expert(I am tired of paying them).

I want to call back certain values on my ode during solving. I have watched the tutorial from Chris https://www.youtube.com/watch?v=KPEqYtEd-zY but not clear.

In matlab, I would do it as follows:

```
function [eqn,Qgap,Force,Fr]=navier(t,y)
%parameters
rho=810;
beta=5e8;
r1=0.01;
r2=0.004;
Ap=pi*(0.01^2-0.004^2);
L=0.06;
a=0.01;
f=10;
l=0.01;
Aeff=pi*2*r1*l;
delta=0.007;
N=20;
dx=delta/N;
rad=linspace(r1,r1+delta,N);
vel=y(1:N);
p1=y(N+1);
p2=y(N+2);
x=a*sin(2*pi*f*t);
u=a*2*pi*f*cos(2*pi*f*t);
eqn=zeros(N+2,1);
vel(1)=u;
vel(end)=0;
dudx=[(vel(2)-vel(1))/dx;(vel(3:end) -vel(1:end-2))/(2*dx);(vel(end)-vel(end-1))/dx];
dudx2=(vel(3:end)-2*vel(2:end-1)+vel(1:end-2))/(dx*dx);
dudx2 = [(dudx(1)-dudx(2))/dx;dudx2;(dudx(end-1)-dudx(end))/dx];
mu=[630 * (1+(0.05*(dudx)).^2).^(-0.23)];
pf=12*a*0.707*u*cos(2*pi*f*t)/(delta^2)*630*(1+(0.05*(0.707*u/delta)^2))^(-0.23);
Qgap =simpsons(2*pi*transpose(rad).*vel,r1,r1+delta);
% Qgap=trapz(rad,2*pi*transpose(rad).*vel);
eqn(1)=(p1-p2+pf)/l + ((mu(1))/rho)*dudx2(1);
eqn(2:N-1)=(p1-p2+pf)/l + ((mu(2:N-1))./rho).*dudx2(2:N-1);
eqn(N)=(p1-p2+pf)/l + ((mu(N))/rho)*dudx2(N);
eqn(N+1)=(beta/(Ap*(L-l-x)))*(-Qgap+Ap*u);
eqn(N+2)=(beta/(Ap*(L-l+x)))*(Qgap-Ap*u);
Force=(p1-p2+pf)*Ap;
Fr=mu(1)*Aeff*dudx(1);
end
```

In matlab, we just have to put the variables as outputs after the eqn, then write a callback function (a bit complicated version of my own)

```
[~,Qgap,Force,Fr] = cellfun(@(tsol,ysol) navier(tsol,ysol.'), num2cell(tsol), num2cell(ysol,2),'uni',0);
Qgap=cell2mat(Qgap);
Force=cell2mat(Force);
Fr=cell2mat(Fr);
```

where as it gives me back a cell of the values with the time points, and then convert to a matlab simple array.

Can you help me achieve this in Julia?