The code is plotting $R_0$ against two parameters

I have been trying to run this code but it give me this error:

Error in Testing_1 (line 21)

[c,h] = contourf(alpha_3,alpha_1,R_0',levels);

%Basic Reproduction Number
alpha_m = 1/8.5; %Rate at which exposed men respectively become infectious
alpha_f = 1/22; %Rate at which exposed women respectively become infectious
tau_m = 1/8.5; %Rate at which infectious men respectively recover
tau_f = 1/21; %Rate at which infectious women respectively recover
beta_mm = 0.23; %Transmission probability from infectious men having sex with susceptible men
beta_ff = 0.18; %Transmission probability from infectious women having sex with susceptible women
beta_mf = 0.01; %Transmission probability from infectious men having sex with susceptible women
beta_fm = 0.18; %Transmission probability from infectious women having sex with susceptible men
alpha_1 = 0.01; %Modification parameters in reducing transmission
alpha_2 = 0.1; %Modification parameters in reducing transmission
alpha_3 = 1.5; %Modification parameters in reducing transmission
I_f = 27; %Population of infectious women
I_m = 28.22; %Population of infectious men
R_0 = (alpha_3 * beta_ff * tau_m + beta_mm * tau_f)/(2 * tau_f * tau_m) + sqrt(4*alpha_1*alpha_2*beta_fm*beta_mf*tau_f*tau_m + alpha_3^2*beta_ff^2*tau_m^2 - 2*alpha_3 * beta_ff * beta_mm * tau_f * tau_m + beta_mm^2 * tau_f^2)/(2 * tau_f * tau_m);
% plot
levels = (0:0.2:1.2);
[c,h] = contourf(alpha_3,alpha_1,R_0',levels);

Error using contourf
Z must be at least a 2x2 matrix.

clabel(c,h)
h.LineWidth = 2; % contour line width (up to you)
xlabel('\alpha_3');
ylabel('\alpha_1');
colormap(jet(numel(levels)-1));
colorbar('vert');

I will appreciate a response.

[Dyuman Joshi]

As the error clearly states, Z i.e. the 3rd input to contourf in the syntax used, should be atleast a 2x2 matrix.

In your case it isn't, it's 1x1.

[Codex]

My aim is to have contour plot (R0 against some parameters) in this image representation:

[Dyuman Joshi]

For that, you will need x and y parameters that vary as well.

The x and y parameters you have (alpha3 and alpha1) are singular.

[Codex]

Thanks so much for your response.

How can I represent that or can you help with it

[Dyuman Joshi]

I do not know what you are trying to do. The comments tell what each parameter is, but does not give an overall idea as to what the objective is.

So, what is the objective?

What does R_0, alpha1 and alpha3 represent?

[Codex]

R_0 represent basic reproduction number.

alpha_1 = 0.01; %Modification parameters in reducing transmission

alpha_3 = 1.5; %Modification parameters in reducing transmission

This is to investigate the relation of the basic reproduction number (R_0) against the alpha_1 and alpha_3. And it can be R_0 against beta_mm

[Dyuman Joshi]

It's not possible to draw a surface plot with scalar data.

You can see that in the answer below, Walter has defined alpha_1 and alpha_3 as grids, only then a surface plot is obtained.

Are you using a research paper as reference and trying to reproduce some results? If so, then please share additional information regarding it.

Answer 1

[Walter Roberson]

I had to guess about the range of alpha_1 and alpha_3 that you wanted to plot.

The contour turns out solid color because the values of R_0 are mostly more than max(levels)

The surface is pretty boring except for a small area near the origin. And if you go too far from the origin then there is a part where the surface goes complex valued. So you would need to tell us what plot range to look at.

%Basic Reproduction Number
alpha_m = 1/8.5; %Rate at which exposed men respectively become infectious
alpha_f = 1/22; %Rate at which exposed women respectively become infectious
tau_m = 1/8.5; %Rate at which infectious men respectively recover
tau_f = 1/21; %Rate at which infectious women respectively recover
beta_mm = 0.23; %Transmission probability from infectious men having sex with susceptible men
beta_ff = 0.18; %Transmission probability from infectious women having sex with susceptible women
beta_mf = 0.01; %Transmission probability from infectious men having sex with susceptible women
beta_fm = 0.18; %Transmission probability from infectious women having sex with susceptible men
%alpha_1 = 0.01; %Modification parameters in reducing transmission
alpha_2 = 0.1; %Modification parameters in reducing transmission
%alpha_3 = 1.5; %Modification parameters in reducing transmission
I_f = 27; %Population of infectious women
I_m = 28.22; %Population of infectious men
% plot
levels = (0:0.2:1.2);

[alpha_1, alpha_3] = meshgrid(0:0.005:0.03, 1:0.05:2);
R_0 = (alpha_3 .* beta_ff .* tau_m + beta_mm .* tau_f)./(2 .* tau_f .* tau_m) + sqrt(4 .* alpha_1 .* alpha_2 .* beta_fm .* beta_mf .* tau_f .* tau_m + alpha_3.^2 .* beta_ff.^2 .* tau_m.^2 - 2 .* alpha_3 .* beta_ff .* beta_mm .* tau_f .* tau_m + beta_mm.^2 .* tau_f.^2) ./ (2 .* tau_f .* tau_m);

  Name          Size            Bytes  Class     Attributes

  I_f           1x1                 8  double              
  I_m           1x1                 8  double              
  R_0          21x7              1176  double              
  alpha_1      21x7              1176  double              
  alpha_2       1x1                 8  double              
  alpha_3      21x7              1176  double              
  alpha_f       1x1                 8  double              
  alpha_m       1x1                 8  double              
  beta_ff       1x1                 8  double              
  beta_fm       1x1                 8  double              
  beta_mf       1x1                 8  double              
  beta_mm       1x1                 8  double              
  cmdout        1x33               66  char                
  levels        1x7                56  double              
  tau_f         1x1                 8  double              
  tau_m         1x1                 8  double              

[c,h] = contourf(alpha_3,alpha_1,R_0,levels);
clabel(c,h)
h.LineWidth = 2; % contour line width (up to you)
xlabel('\alpha_3');
ylabel('\alpha_1');
colormap(jet(numel(levels)-1));
colorbar('vert');

figure()
surf(alpha_3,alpha_1,R_0);
view(3)