Saving figures and automatic legend

I tried this

ax = gca;

exportgraphics(ax,'myplot.png','Resolution',300)

but is saving only the last plot. I also want automatic legend. Below is my code:

%% initialization

clear

clc

close all

%% Model parameters

global k1 eta1 alpha3 gamma1 d N Phi xi h A B C G

k1 = 6*10^(-12); % elastic constant

eta1 = 0.0240; % viscosity

xi = -1; % activity parameter

alpha3 = -0.001104; % viscosity

gamma1 = 0.1093; % viscosity

Theta = 0.0001;

% Simplify model parameters

A = k1/gamma1;

B = alpha3/gamma1;

C = eta1 - alpha3*B;

G = alpha3*A;

d = 0.0002;

N = 200;

%% Numerical setup

% step size

h = d/N;

% t span

tspan = [0 100];

% range of z

%z=linspace(0,d/2,N+1)

z=linspace(0,d,N+1);

% initial conditions

theta0 = Theta*sin(pi*z/d);

v0 = zeros(1,N+1);

theta0_int=theta0(2:N);

v0_int=v0(2:N);

u0 = [theta0_int'; v0_int'];

% Constant mass matrix M: We use M to represent the left hand side of the system of equations.

M1=eye(N-1,N-1);

M2=zeros(N-1,N-1);

M=[M1 M2;M2 M2];

% Boundary Conditions

Phi = 0;

%% ode solver

options = odeset('Mass',M,'RelTol',1e-4,'AbsTol',1e-6);

[t,y] = ode15s(@lcode1,tspan,u0, options);

theta_middle = y(:,N/2); % theta at the middle of the layer (i.e., z=d/2)

% Extract the solution for theta and v

theta = [Phi*ones(length(t), 1) y(:,1:N-1) Phi*ones(length(t), 1)];

v = [zeros(length(t), 1) y(:,N:(2*N-2)) zeros(length(t), 1)];

%% Plot the solution.

figure

subplot(2,2,1)

plot(z, theta(1:5,:))

xlabel('z(\mum)')

ylabel('\theta(z,t)(rad)')

title('Director angle','FontSize',10)

%[xmin(z) xmax(z) ymin(theta) ymax(theta)];

subplot(2,2,2)

plot(z, v(1:5,:))

xlabel('z(\mum)')

ylabel('v(z,t)(m/s)')

title('Flow velocity')

%[xmin(z) xmax(z) ymin(theta) ymax(theta)];

subplot(2,2,3)

plot(t,theta_middle)

xlabel('z(\mum)')

ylabel('\theta(d/2,t)(rad)')

title('Director angle at the middle of the layer', 'FontSize',6)

ax = gca;

% Requires R2020a or later

exportgraphics(ax,'modelplot.png','Resolution',300)

%% Functions

% Right hand side of the ODEs: F(U)

function rhsode = lcode1(t,y)

global Phi xi h A B C G N

% initialize theta and v

theta = y(1:(N-1));

v = y(N:(2*N-2));

rhsode(1,1) = (A/(h^2))*(theta(2)-2*theta(1)+ Phi) - (B/(2*h))*(v(2)-0);

% for all other internal positions 0<z<d

for i=2:(N-2)

rhsode(i,1) = (A/(h^2))*(theta(i+1)-2*theta(i)+theta(i-1)) - (B/(2*h))*(v(i+1)-v(i-1));

end

% for the positon to the left of the right hand boundary z=d

rhsode(N-1,1) = (A/(h^2))*(Phi-2*theta(N-1)+ theta(N-2)) - (B/(2*h))*(0-v(N-2));

rhsode(N,1) = (G/(h^3))*(-Phi + 3*theta(1) - 3*theta(2) + theta(3)) + (C/(h^2))*(v(2) -2*v(1)+ 0) + (xi/(2*h))*(theta(2)-Phi);

rhsode(N+1,1) = (G/(2*h^3))*(Phi - 2*theta(1) + 2*theta(3)- theta(4)) + (C/(h^2))*(v(3) -2*v(2) + v(1)) + (xi/(2*h))*(theta(3)-theta(1));

% for all other internal positions 0<z<d

for i=(N+2):(2*N-4)

rhsode(i,1) = (G/(2*h^3))*(theta(i-2-(N-1)) - 2*theta(i-1-(N-1)) + 2*theta(i+1-(N-1))- theta(i+2-(N-1))) +(C/(h^2))*(v(i+1-(N-1)) -2*v(i-(N-1)) + v(i-1-(N-1))) + (xi/(2*h))*(theta(i+1-(N-1))-theta(i-1-(N-1)));

end

% for the two positons to the left of the right hand boundary z=d

rhsode(2*N-3,1) = (G/(2*h^3))*(theta(N-4) - 2*theta(N-3) + 2*theta(N-1) - Phi) +(C/(h^2))*(v(N-1) -2*v(N-2) + v(N-3)) + (xi/(2*h))*(theta(N-1)-theta(N-3));

rhsode(2*N-2,1) = (G/(h^3))*(-theta(N-3) + 3*theta(N-2) - 3*theta(N-1) + Phi) +(C/(h^2))*(0 -2*v(N-1) + v(N-2)) + (xi/(2*h))*(Phi-theta(N-2));

end

Answer 1

[dpb]

You only saved a handle to the current axes via gca at the end -- but you created three (3) axes via subplot

Save the handles of the axes when you create them and then export each in turn, using the array of axes handles you just saved at the end.

[University Glasgow]

Hi,

Thank you for your response but I wanna save all of them together…

[dpb]

In that case it's the figure handle you want, not the axes...

hF=gcf;
exportgraphics(hF,'modelplot.png','Resolution',300)

See exportgraphics description for details on object handle input argument.

[University Glasgow]

Thank you very much.