Since i am using matlab ode23s solver, it contains two matlab files . One contain the differential equations and another contains plotting and to run the m-files.
The code are working perfectly. Now i want to know the time step size that is using on the plot. How can i get the output of time step size. I would like to know the time step size that is using on the plot too. please help me.
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Code:
% 3 Nonlinear differential equations after Asymptotic expansion
% with 1-c in dc/dt differential equation
function xpr= no(t,x)
%values of parameters
k_f= 6.7*10.^7;
k_d= 6.03*10.^8;
k_n=2.92*10.^9;
k_p=4.94*10.^9;
%Unknown parameters
lambda_b= 0.0087;
% scale parameters
K_F= k_f * 10.^-9;
K_D= k_d * 10.^-9;
K_N= k_n * 10.^-9;
K_P= k_p * 10.^-9;
LAMBDA_B= lambda_b*10.^-9;
%Pool Values
P_C= 3 * 10.^(11);
P_Q= 2.87 * 10.^(10);
% initial conditions
c_0=x(1);
s_0=x(2);
q_0=x(3);
%Non-linear differential equations.
% dc_0/dtau= c_0*(- K_F - K_D - K_N * s_0 - K_P*(1-q_0))
% ds_0/dtau = Lambda_B * c* P_C *(1-s_0)
% dq_0/dtau = (1-q_0)* K_P * c_0 *(P_C / P_Q)
xpr= zeros(3,1);
xpr(1)= c_0*(- K_F - K_D - K_N * s_0 - K_P*(1-q_0));
xpr(2)= LAMBDA_B * c_0* P_C *(1-s_0);
xpr(3)= (1-q_0)* K_P * c_0 *(P_C / P_Q);
xpr= [xpr(1);xpr(2);xpr(3)];
% TO RUN the 3 nonlinear differential equations after asymptotic expansion.
% with 1-c in dc/dt differential equation
format bank
close all;
clear all;
clc;
%time interval
ti=0;
tf=0.2;
tspan=[ti tf];
x0=[0.25 0.02 0.98]; %initial conditions
%time interval of [0 2] with initial condition vector [0.25 0.02 0.98] at time 0.
options= odeset('RelTol',1e-4, 'AbsTol',[1e-4 1e-4 1e-4]);
[t,x]= ode23s(@no,tspan,x0,options);
%Plotting the graphs:
figure
subplot(3,1,1), plot(t,x(:,1),'r'),grid on;
title('3 nonlinear differential equations (with 1-c)'),ylabel('c_0');
subplot(3,1,2), plot(t,x(:,2),'b'),grid on;
ylabel('s_0');
subplot(3,1,3), plot(t,x(:,3),'g'),grid on;
ylabel('q_0');xlabel('Time')