Find relation of initial value and maximum of the value by solving this odes

by solving this ode, we could get the relation plot of r and m (assuming =2,=0),

now I want to change the value of (between 0-4) to get maximum of munder each , and I also want to plot , could anyone help me? thank you!

basic code between m-r like this:

fun2.m

function dtm=func2(r,tm)
dtm=zeros(2,1);

dtm(1)=(-4)*(sinh(tm(1))-2*sinh(tm(1)/2))*(r^3*(sinh(tm(1)) ...
    -8*sinh(tm(1)/2)+3*tm(1))+tm(2))/((3*tm(1))*(tm(1)-2*tm(2))* ...
    (cosh(tm(1))-4*sinh(tm(1)/2)+3));
dtm(2)=(r^2)*(sinh(tm(1))-tm(1));

and here is the main.m

rspan=[0 20];
y0=[2;0];
[r,y]=ode45(@func2,rspan,y0);

subplot(1,2,1)
plot(r,y(:,2),'b-');
M=max(y(:,2));
grid on;
title('m-r');
axis([0 4 0 2])
xlabel('r'); ylabel('m');
legend('y_1','y_2')


subplot(1,2,2)