# For a beginning Matlab plotting project instructions are to use several commands. I used everything except for "subplot" and "hold". Can anyone tell me how I could work it into the following code?:

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cassie on 5 Feb 2014
Edited: Amit on 5 Feb 2014
%Define parameters of r and functions
r=0:.1:1;
Ea=-1.436./r;
Er=(5.86.*10.^-6)./(r.^9);
En=Ea+Er;
%plot functions with given r values
plot(r,Ea,'--',r,Er,'-',r,En,':')
%set axis according to the best fit for pertinent information
axis ([0 1 -15 15]);
%Display equations on graph, modified according to in-class example
text(.20,-10,'Ea=$\displaystyle\frac{-1.436}{r}$','interpreter','LaTeX') text(.7,3,'Er=$\displaystyle\frac{5.86*10.^-6}{r.^9}$','interpreter','latex') text(.05,0,'En=$En+Ea$,','interpreter','latex')
% Create xlabel
xlabel({'Interatomic Separation,r, nm'});
% Create ylabel
ylabel({'Potential Energy, E'});
% Create title
title({'K.^+ -C.^- Ion Pair, Attractive, Repulsive, and Net Energies'});
% Create textbox
annotation('textbox',... [0.73 0.78 0.17 0.13],... 'String',{'Name','Net id:00000','Feb. 4, 2013'},... 'FitBoxToText','off');
%Create legend, specify location
hleg1=legend('Attractive Force (Ea)','Repulsive Force (Er)','Net Energy (En)'); set(hleg1,'location','SouthEast');
cassie on 5 Feb 2014
Edited: cassie on 5 Feb 2014
For example, could I use a subplot command and superimpose that onto the graph I did using the plot command? Or is that question only illustrating how clueless I am? I'm perfectly happy with the way it looks... but I'll lose points for not using the additional commands.
Image Analyst on 5 Feb 2014
Then split it into two calls to plot() like Amit showed you. It will plot in two separate graphs/charts, instead of both on one graph.

Amit on 5 Feb 2014
Edited: Amit on 5 Feb 2014
subplot sections a figure windows in sections For example,
subplot(3,2,1)
Suggest that the figure space is going to be distributed into 3 row and 2 columns (total 3X2 = 6) spaces. The last index (here, 1) suggests which of these spaces you're using right now.
Just to understand, try something like this:
x = 1:10; % Random functions
y1 = 5*x;
y2 = exp(x);
subplot(2,2,1);
plot(x,y1);
subplot(2,2,2);
plot(x,y2);
And see where each of the plots are plotted.
Everytime you call subplot, it is very similar to calling figure. However, figure creates a new figure window and makes that your current figure. Any thing you will plot will be plotted on that figure. Similar to that, when you call subplot, the axes of that section becomes your current axes.
cassie on 5 Feb 2014
It's becoming clearer. I had to turn it in but I "followed" the directions by adding
subplot(1,1,1)
hold on
above my plot command... which does nothing but doesn't throw an error. Maybe I'll get full credit for being creative. Thanks again for your help.
Amit on 5 Feb 2014
Edited: Amit on 5 Feb 2014
If you really have to use hold on, you can do this:
plot(r,Ea,'--');
hold on;
plot(r,Er,'-');
plot(r,En,':');
This will plot it exactly the same.

Image Analyst on 5 Feb 2014
subplot() just tells it WHERE to plot. plot() does the actual plotting. Since you have only a single plot, I don't see any reason to use subplot().
hold on tells it not to blow away any existing plot when you plot another one - it will keep both. Since you are not calling plot() more than once, you will not need to use hold.
cassie on 5 Feb 2014
Thanks for the link, I was trying to figure out how to incorporate subplot and hold without destroying the look of what I already created. Not because I want to, just trying to follow general instructions for the project.