plot(z, f1(xi(i)))
assign the result of f1(xi(i)) to a variable, say f1i. Then
h(i, :) = plot(z, f1i(:, 1), 'b', f1i(:, 2), 'r');
Now delete the legend call inside the loop.
After the loop
legend(h(1,:), {'\xi=-0.06', '\xi=-0.05'})
Legend for varying parameters in a loop
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Is it possible to have legends such that for xi=-0.06 (I have 4 different plots for various times). I want the lines to have the same color(say blue) and for xi=-0.05 (I have 4 different plots for various times) I want the lines to have the same color(say red)? See the lines concern and I have also attached my codes
f1 = @(xi) theta(1:round(nt/4):nt,:);
hold on
for i = 1:numel(xi)
plot(z, f1(xi(i)))
xlabel('t (seconds)')
ylabel('\theta(z,t)(rad)')
legend('\xi=-0.06', '\xi=-0.05')
end
hold off
回答（1 个）
Walter Roberson
2022-9-16
24 个评论
University Glasgow
2022-9-16
编辑：University Glasgow
2022-9-16
Thank you.
f1 = @(xi) theta(1:round(nt/4):nt,:);
hold on
for i = 1:numel(xi)
f1i = f1(xi(i));
h(i, :) = plot(z, f1i(:, 1), 'b', z, f1i(:, 2), 'r');
xlabel('t (seconds)')
ylabel('\theta(z,t)(rad)')
end
legend(h(1,:), {'\xi=-0.06', '\xi=-0.05'})
hold off
I tried it but I received this error:
Error using plot Vectors must be the same length.
Error in Revised_Case1_Ijuptilk (line 93)
h(i, :) = plot(z, f1i(:, 1), 'b', f1i(:, 2), 'r');
Walter Roberson
2022-9-16
your code is different than your error message. the code in your error message does not have the second z
I just noticed that your f1 ignores its input so you are drawing the same thing each iteration, which sounds wrong.
how many columns does theta have? How long is z?
University Glasgow
2022-9-16
Still same thing without the second z.
f1 = @(xi) theta(1:round(nt/4):nt,:);
hold on
for i = 1:numel(xi)
f1i = f1(xi(i));
h(i, :) = plot(z, f1i(:, 1), 'b', f1i(:, 2), 'r');
xlabel('t (seconds)')
ylabel('\theta(z,t)(rad)')
end
legend(h(1,:), {'\xi=-0.06', '\xi=-0.05'})
hold off
Torsten
2022-9-16
size(z) cannot be 31. It must either be 31x1 or 1x31, and which of the two is correct is important.
Torsten
2022-9-16
h(i, :) = plot(z, f1i(1,:), 'b', f1i(2,:), 'r');
instead of
h(i, :) = plot(z, f1i(:, 1), 'b', f1i(:, 2), 'r');
University Glasgow
2022-9-16
With the code below, I don't think f1i are the same:
f1 = @(xi) theta(1:round(nt/4):nt,:);
hold on
for i = 1:numel(xi)
plot(z, f1(xi(i)))
xlabel('t (seconds)')
ylabel('\theta(z,t)(rad)')
legend('\xi=-0.06', '\xi=-0.05')
end
hold off
You can see from the figures I attached: The figure for xi =[-0.06, -0.05] and xi =[-0.06, -0.06] are different. Remember I have loop over my solver for xi.
Torsten
2022-9-16
编辑：Torsten
2022-9-16
How should the f1i be different if the function f1 does not depend on xi ?
This can only happen if theta has changed because of an outer loop over the xi.
But then, your inner loop from above - also over xi - cannot make sense.
Please include the code you use at the moment.
Torsten
2022-9-16
%% initialization
clear
clc
close all
%% Model parameters
global N Phi A B C G h
k1 = 6*10^(-12); % elastic constant
eta1 = 0.0240; % viscosity
alpha3 = -0.001104; % viscosity
gamma1 = 0.1093; % viscosity
Theta = 0.0001;
d = 0.0002;
% Simplify model parameters
A = k1/gamma1;
B = alpha3/gamma1;
C = eta1 - alpha3*B;
G = alpha3*A;
N = 30; % N must be even
%% Numerical setup
% step size
h = d/N;
% t span
tspan = [0:100];
nt=length(tspan);
% range of z
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
for xi = [-0.06, -0.05]
options = odeset('Mass',M,'RelTol',1e-4,'AbsTol',1e-6);
[t,y] = ode15s(@(t,y)lcode1(t, y, xi),tspan,u0, options);
% 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)];
% Extract theta solution for different value
mytheta= xlsread('thetasolxi1.xlsx');
thetasolxi = mytheta(:,[2, 4, 6]);
z1 = mytheta(:,1);
% Extract v solution for different value
myvol= xlsread('vsolxi1.xlsx');
vsolxi = myvol(:,[2, 4, 6]);
z2 = myvol(:,1);
% theta at the middle of the layer (i.e., z=d/2)
theta_middle = theta(:, N/2);
%% Extract theta_middel data from maple
mydata= xlsread('DatafromMaple_middle.xlsx');
theta_middlemaple = mydata(:,2);
time = mydata(:,1);
% Extract r(q) data from maple
rqdata= xlsread('rqdata.xlsx');
rq= rqdata(:,2);
qsize = rqdata(:,1);
% % theta plot for different xi values
f1 = @(xi) theta(1:round(nt/4):nt,:);
hold on
for i = 1:numel(xi)
plot(z, f1(xi(i)))
xlabel('t (seconds)')
ylabel('\theta(z,t)(rad)')
legend('\xi=-0.06', '\xi=-0.05')
end
hold off
end
% %% Plot the solution.
% figure
% subplot(2,1,1)
% plot(z, theta(1:round(nt/10):nt,:))
% xlabel('z(\mum)')
% ylabel('\theta(z,t)(rad)')
%
% subplot(2,1,2)
% plot(z, v(1:round(nt/10):nt,:))
% xlabel('z(\mum)')
% ylabel('v(z,t)(m/s)')
% %legend('t_0 =0', 't_1=10', 't_2=20', 't_3=30', 't_4=40', 'Location','bestoutside')
%
% % matlab and maple for thetamiddle plot
% figure
% hold on
% plot(t,theta_middle, 'r', MarkerSize=2)
% plot(time,theta_middlemaple, 'b--', MarkerSize=2)
% xlabel('t (seconds)')
% ylabel('\theta(d/2,t)(rad)')
%
%
% % matlab and maple for theta plot for different xi values
% figure
% hold on
% plot(z, theta(end, :))
% plot(z1, thetasolxi./2, 'r', MarkerSize=2)
% xlabel('t (seconds)')
% ylabel('\theta(z,t)(m/s)')
%
%
% % matlab and maple for v plot for different xi values
% figure
% hold on
% plot(z, v(end, :))
% plot(z2, vsolxi./2, 'r', MarkerSize=2)
% xlabel('t (seconds)')
% ylabel('v(z,t)(m/s)')
%
%
% % r(q) equation
% alpha=1-alpha3^2/gamma1/eta1;
% q=0:0.001:(5*pi);
% r=q-(1-alpha)*tan(q)+(alpha3*xi*alpha/eta1)./(4*k1*q.^2/d^2-alpha3*xi/eta1).*tan(q);
%
% % Plotting r(q)
% figure
% plot(q,r, 'b--', MarkerSize=2)
% xlabel('t (seconds)')
% ylabel('\theta(d/2,t)(rad)')
% %legend('\xi=-0.02','\xi=0.01', '\xi=0.02')
% axis([0 5*pi -20 20])
%% Definition of Functions
% Right hand side of the ODEs: F(U)
function rhsode = lcode1(t, y ,xi)
global N Phi A B C G h
% initialize theta and v
theta = y(1:(N-1));
v = y(N:(2*N-2));
% theta equations
% for the positon to the right of the left hand boundary z=0
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));
% v equations [REMEMBER theta the RHS index for the v equations is N-1 more than the indices of the theta and v variables in this function]
% for the two positons to the right of the left hand boundary z=0
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
Torsten
2022-9-16
编辑：Torsten
2022-9-16
It makes no sense to make a plot loop over the xi before the calculations for all the xi have finished .
Save the solution for theta and v first in 3d-arrays (the 3rd dimension respects the different xi) and plot after all calculations have finished outside the calculation loop
for xi = [-0.06, -0.05]
...
end
University Glasgow
2022-9-16
编辑：University Glasgow
2022-9-16
Please how I theta and v first in 3d-arrays?
Torsten
2022-9-16
counter = 0;
for xi = [-0.06, -0.05]
options = odeset('Mass',M,'RelTol',1e-4,'AbsTol',1e-6);
[t,y] = ode15s(@(t,y)lcode1(t, y, xi),tspan,u0, options);
% 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)];
% Extract theta solution for different value
mytheta= xlsread('thetasolxi1.xlsx');
thetasolxi = mytheta(:,[2, 4, 6]);
z1 = mytheta(:,1);
% Extract v solution for different value
myvol= xlsread('vsolxi1.xlsx');
vsolxi = myvol(:,[2, 4, 6]);
z2 = myvol(:,1);
% theta at the middle of the layer (i.e., z=d/2)
theta_middle = theta(:, N/2);
%% Extract theta_middel data from maple
mydata= xlsread('DatafromMaple_middle.xlsx');
theta_middlemaple = mydata(:,2);
time = mydata(:,1);
% Extract r(q) data from maple
rqdata= xlsread('rqdata.xlsx');
rq= rqdata(:,2);
qsize = rqdata(:,1);
counter = counter + 1;
Theta(counter,:,:) = theta;
V(counter,:,:) = v;
end
University Glasgow
2022-9-16
Wow, I see what you mean now. I really appreciate your help. Now the dimension of Theta and V is now 2x101x31 respectively. Please how do I extract Theta and V in 2D ?
University Glasgow
2022-9-19
编辑：Walter Roberson
2022-9-19
Hi, pleae why does this gives me the same plot?
xi = [-0.06, -0.1];
figure
hold on
for ixi = 1:numel(xi)
plot(z, squeeze(THETA(ixi,1:round(nt/4):nt,:)));
end
hold off
I was expecting my first plot to corresponds to xi =-0.06 and the second plot to corresponds to xi = -0.1 but I got the same plot.
Torsten
2022-9-19
编辑：Torsten
2022-9-19
I don't know. I get all curves stored in the plot.
f1 = @(x) x.^2;
f2 = @(x) exp(x);
z = 0:0.01:1;
THETA(1,:,:) = [f1(z);f2(z)];
THETA(2,:,:) = 3*THETA(1,:,:);
size(THETA)
ans = 1×3
2 2 101
figure
hold on
for ixi = 1:2
if ixi == 1
plot(z, squeeze(THETA(ixi,:,:)),'r');
else
plot(z, squeeze(THETA(ixi,:,:)),'b');
end
end
grid on
hold off
University Glasgow
2022-9-19
The code I have here gives legend with same color for corresponding values of xi, which is okay. But I want the legend to appear such that for xi=-0.06 (r), for xi=-0.2 (b) and for xi=-0.06 (c) with only one line representing the 3 lines instead of 3 lines for each value of xi. I don't know if this is possible.
hold on
for ixi = 1:3
if ixi == 1
plot(z, squeeze(THETA(ixi,1:round(nt/3):nt,:)),'r--', 'DisplayName','\xi=-0.06');
elseif ixi==2
plot(z, squeeze(THETA(ixi,1:round(nt/3):nt,:)),'b', 'DisplayName','\xi=-0.2');
else
plot(z, squeeze(THETA(ixi,1:round(nt/3):nt,:)),'c', 'DisplayName','\xi=-0.1');
end
xlabel('t (seconds)')
ylabel('\theta(z,t)(rad)')
end
另请参阅
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