# i need the second plot to start from where the last point on the first plot left off. The graph is meant to be continuous across all three stages not broken up. Help please?

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Chukwunememma Uponi on 1 Dec 2019
Answered: Dhananjay Kumar on 4 Dec 2019
close all
clc;
%define variables
mi_1=2290000;
mf_1=130000;
tb_1=165;
Isp_1=263;
mi_2=496200;
mf_2=40100;
tb_2=360;
Isp_2=421;
mi_3=123000;
mf_3=13500;
tb_3=500;
Isp_3=421;
g=9.81; %acceleration due to gravity
%stage 1
t_1=linspace(0,165);
mr_1=mi_1-((mi_1-mf_1)*(t_1/tb_1));
u_1=g.*(Isp_1.*log(mi_1./mr_1)-t_1); %velocity function
a_1=gradient(u_1, t_1(2)-t_1(1)); %differentiation of velocity function to get acceleration
p_1= cumtrapz(t_1,u_1); %integration of velocity function to get position
%end of stage 1
%stage 2
t_2=linspace(165,525);
mr_2=mi_2-((mi_2-mf_2)*(t_2/tb_2));
u_2=g.*(Isp_2.*log(mi_2./mr_2)-t_2);
p_2= cumtrapz(t_2,u_2);
%end of stage 2
%stage 3
t_3=linspace(525,1025);
mr_3=mi_3-((mi_3-mf_3)*(t_3/tb_3));
u_3=g.*(Isp_3.*log(mi_3./mr_3)-t_3);
p_3= cumtrapz(t_3,u_3);
%end of stage 3
%position-time graph
figure
plot(t_1,p_1,'blue',t_2,p_2,'blue',t_3,p_3,'blue')
title('Position')
ylabel('height[m]')
xlabel('time[s]')

Dhananjay Kumar on 4 Dec 2019
Just shift the plot by adding the previous segment's final y-value:
plot(t_1,p_1,'blue',t_2,p_2+p_1(end),'blue',t_3,p_3+p_1(end)+p_2(end),'blue')