hold on does not work

A = 0.06;
k_l = 26400; %Linear stiffness
m = 483; %Mass
f = @(t,x,Om,l,k_s,d) [ x(2); ...
            -(2*k_s*(x(1)-(A*sin(Om*t))))* ...
            (sqrt((l-d)^2 + (x(1)-(A*sin(Om*t)))^2) - l)/ ...
            (m*(sqrt((l-d)^2 + (x(1)-(A*sin(Om*t)))^2))) ];
%%
Om_array = linspace(0,20,21); %in rad/s-1
l_array = linspace(0.2,1,21);
[om_array, L_array] = meshgrid(Om_array, l_array);
d = linspace(-0.005, -0.03, 10);
%d = -1;
Response_amp = zeros([size(Om_array), numel(d)]);
T = 150;
x0 = [0,0];
for k=1:numel(d)
    for i=1:numel(Om_array)
        for j=1:numel(l_array)
            Om = om_array(i,j);
            l = L_array(i,j);
            k_s = -(k_l*(l-d))/(4*d); %Spring stiffness
            
            [t, x] = ode45(@(t,x) f(t,x,Om,l,k_s,d(k)),[100,T],x0);
            Response_amp(i,j,k) = (max(x(:,1)) - min(x(:,1)))/2;
        end
    end
end
%% plot
figure(1);
ax = axes();
view(3);
hold(ax);
view([30 33]);
grid on
for i=1:size(Response_amp,3)
    mesh(om_array/(2*pi),L_array,Response_amp(:,:,i));
end


hold on


d = -1;
Response_amp = zeros([size(Om_array), numel(d)]);
T = 150;
x0 = [0,0];
for k=1:numel(d)
    for i=1:numel(Om_array)
        for j=1:numel(l_array)
            Om = om_array(i,j);
            l = L_array(i,j);
            k_s = -(k_l*(l-d))/(4*d); %Spring stiffness
            
            [t, x] = ode45(@(t,x) f(t,x,Om,l,k_s,d(k)),[100,T],x0);
            Response_amp(i,j,k) = (max(x(:,1)) - min(x(:,1)))/2;
        end
    end
end
%% plot
%figure(1);
ax = axes();
view(3);
hold(ax);
view([30 33]);
grid on
for i=1:size(Response_amp,3)
    mesh(om_array/(2*pi),L_array,Response_amp(:,:,i));
end

xlabel('Frequency (Hz)')
ylabel('Length of the spring (m)')
zlabel('Response Amplitude (m)')
set(gca,'FontSize',15)


hold off

Hi, this code represents different graphs depending on the value of d. Firstly, d is set to be linspace(-0.005, -0.03, 10). Then, by using hold on, I have added single value of d as being -1. However, this code gives me separate 2 graphs rather than being merged. How do I solve this problem?

Thanks for reading.

Answer 1

[Mehmed Saad]

ax = axes();

creates new axes on current figure. so call it once

hold(ax)

will hold on or hold off the axes. when you call it first time it add nextplot, when you call it again it replace nextpot

for example

figure,
ax = axes;
plot(rand(1,10))
hold(ax)

Now check if nextplot property is replace or add

ax.NextPlot

ans =

    'add'

Now call it again

hold(ax)

now check Nextplot property

ax.NextPlot

ans =

    'replace'

So you need to comment out these two lines from your code (where you plot the 2nd time, for first time it is fine)