Plotting Multiple Curves on the Same Graph

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Hollis Williams on 16 Jul 2019
Commented: Star Strider on 18 Jul 2019
I am plotting a graph of radial velocity against varying radius, but there is also a parameter in the velocity expression similar to the Reynolds number which can have various values, so I would like to set the value of the parameter to 0, 1 and 0.2 and to plot three curves on the same graph, what would be the easiest way to do this?
doc hold
Set e.g.
hold( hAxes, 'on' )
for your axes with handle hAxes, then you can add as many plots as you like.
Alternatively if you have all the results together in a matrix (assuming they are the same length for each parameter) you can just plot the matrix all in one go using
doc plot
and making sure you have it oriented the right way.

Star Strider on 16 Jul 2019
It depends on your function and what you want to do:
t = linspace(0, 2*pi);
freq = [1 5 9];
ampl = [1 2 3];
s = bsxfun(@times, ampl(:), sin(freq(:)*t));
figure
plot(t, s)
grid
Star Strider on 18 Jul 2019
As always, my pleasure!
Remember that in my code, ‘bt’ is a function, so it needs to be evaluated in any calculation using it, and that requires that it be supplied with a numeric argument so that it can return a numeric result:
theta = @(R,Kn) (bt(Kn)./(R.^2));
The complete code is now:
bt = @(Kn) -sqrt(pi/2)*(30*Kn.^2 + 180*(1+(1./pi))*Kn.^3)./(20*pi + 135*pi*Kn + 9*(25*pi +18)*Kn.^2 +324*Kn.^3);
theta = @(R,Kn) (bt(Kn)./(R.^2));
Knv = [0, 0.2, 1];
Rv = 1:10;
[Rm,Knm] = meshgrid(Rv,Knv);
figure
plot(Rv, theta(Rm,Knm))
grid
%xlabel('R')
lgdc = sprintfc('K_n = %3.1f', Knv);
legend(lgdc, 'Location','SE')
I tested that to be sure it works. It does.