How to have multiple lines on a graph for different values of a parameter.

조회 수: 2 (최근 30일)
Hello,
I'm trying to vary the parameter 'k' from 0 to 4 in this code. However, there is an error because the blue lines in the plot should not be shooting out to the right. Can anyone see what I am doing wrong?
Thanks!
%Clear command window and workspace
clear
close all
clc
% Fitzhugh-Nagoma model parameters
e=0.01; k=1:1:4; a=0.1;
i = 0.001;
figure(1);
hold on
u=zeros(500000,4);
v=zeros(500000,4);
t=zeros(100000,1);
% Initial conditions:
u(:)=0.6;
v(:)=0.0;
t(1)=0;
dt=0.001;
%==========================================================================
% Forvard Euler Method, for soluing the ODE
%==========================================================================
for i=1:1:500000
t(i+1)=t(i)+dt;
% u(i+1) = u(i)+ dt*((1/e)*((k(:)*u(i)*(u(i)-a)*(1-u(i)))-v(i)));
u(i+1,:) = u(i,:)+ dt*((1/e)*((k*(u(i,:)*(u(i,:)-a)*(1-u(i,:))))-v(i)));
v(i+1,:) = v(i,:)+ dt*(u(i)-v(i));
end
% Getting the phase plot
figure(1);
upts=(-2:.05:2);
unullpts=(k(:)*upts.*(upts-a).*(1-upts));
vnullpts=upts;
plot(upts,unullpts,'black',upts,vnullpts,'black');
xlabel('u'); ylabel('v');
axis([-1 2 -1.5 5]);
plot(u,v,'b')
title('Nullcline Plot')
xlabel('u')
ylabel('v')

채택된 답변

madhan ravi
madhan ravi 2018년 11월 6일
편집: madhan ravi 2018년 11월 6일
EDITED
%Clear command window and workspace
clear
close all
clc
% Fitzhugh-Nagoma model parameters
e=0.01;
k=1:1:4; a=0.1;
i = 0.001;
figure(1);
hold on
u=zeros(500000,4);
v=zeros(500000,4);
t=zeros(100000,1);
% Initial conditions:
u(:)=0.6;
v(:)=0.0;
t(1)=0;
dt=0.001;
%==========================================================================
% Forvard Euler Method, for soluing the ODE
%==========================================================================
for i=1:1:500000
t(i+1)=t(i)+dt;
% u(i+1) = u(i)+ dt*((1/e)*((k(:)*u(i)*(u(i)-a)*(1-u(i)))-v(i)));
u(i+1,:) = u(i,:)+ dt.*((1/e).*((k.*(u(i,:).*(u(i,:)-a).*(1-u(i,:))))-v(i)));
v(i+1,:) = v(i,:)+ dt.*(u(i)-v(i));
end
% Getting the phase plot
figure(1);
upts=(-2:.05:2);
unullpts=(k(1).*upts.*(upts-a).*(1-upts));
vnullpts=upts;
plot(upts,unullpts,'black',upts,vnullpts,'black');
axis([-1 2 -1.5 5]);
hold on
plot(-u,-v,'b')
unullpts=(k(2).*upts.*(upts-a).*(1-upts));
vnullpts=upts;
plot(upts,unullpts,'m');
unullpts=(k(3).*upts.*(upts-a).*(1-upts));
vnullpts=upts;
plot(upts,unullpts,'r');
unullpts=(k(4).*upts.*(upts-a).*(1-upts));
vnullpts=upts;
plot(upts,unullpts,'g');
title('Nullcline Plot')
xlabel('u')
ylabel('v')
  댓글 수: 11
Westin Messer
Westin Messer 2018년 11월 6일
Thanks. Is there any way I can put that in some kind of loop? For example, if I wanted to do 20 different values of k I wouldn't have to write the plot line 20 times.
madhan ravi
madhan ravi 2018년 11월 6일
편집: madhan ravi 2018년 11월 6일
for i = 1:numel(k)
unullpts=(k(i).*upts.*(upts-a).*(1-upts));
vnullpts=upts;
plot(upts,unullpts,'m');
hold on
end
The above does the same work what you want

댓글을 달려면 로그인하십시오.

추가 답변 (0개)

카테고리

Help CenterFile Exchange에서 2-D and 3-D Plots에 대해 자세히 알아보기

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by