%useful commands for clearing everything
clc; clear all; close all; 

tspan = [0 100]; %timespan

%IC = [initial A, initial B]
IC = [0 0] ; 

k_prod = 1; %production rate
k_deg = 0.2; %degradation rate
kd = 1; 

%The extra brackets allow you to add additional variables
%For ode45 the format is ode45(@function, timespan, initial conditions)
[t, C] = ode45(@pos_reg, tspan, IC, [], k_prod,k_deg,kd); 

plot(t,C); 
legend('Protein A','Protein B')
xlabel('Time')
ylabel('Protein Concentration')
title('Positive Regulation')