Calculating growth using ODE 45 from t=0 to t=100

Hello, I need help with my code using ODE 45. Can someone help me check my code?

t = 0:0.01:100;
r = [0.05 0.1 0.5 1 10]; 
k = 15; 
B0 = 1; 
B = @(x,y) 30-x.^2-5*(cos((x.*y)/5)).^2;

colourmap = [228 26 28; 55 126 184; 77 175 74; ...
    152 78 163; 255 127 0]/255;

z = zeros(length(t),length(r));
T = zeros(length(t),length(r));
% 
for i = 1:length(r)
    dBdt = @(B) r.*B*(1-B./k);
    [z,T] = ode45(dBdt,tspan, B0);
    
    plotting
    figure(6) %figure 6
    loglog(t,T,'-','color',colourmap(i,:))
    hold on
    grid on
end

[James Tursa]

Does something seem to be wrong to you? If so, what?