Plotting a Distribution of Molecules

Need a figure for c(x,t)

t1=0;

t2=600;

t3=1200;

t4=1800;

t5=2400;

t6=3000;

t7=3600;

D=5e-9;

Co=1;

𝛿(𝑥−𝑥0)→∞ 𝑎𝑡 𝑥=𝑥0, and 𝛿(𝑥−𝑥0)=0 𝑓𝑜𝑟 𝑥≠𝑥0.

where 𝑐(𝑥,𝑡)= (Co/(sqrt(4*pi*D*t1)))exp^(-(x-xo)^2)/(4*D*t))

Answer 1

[Star Strider]

The erf function is your friend!

Specifically:

x = linspace(-5, 5);
y = gradient(erf(x)) ./ gradient(x);

figure
plot(x, y)
grid

.

[elle morey]

where is the -5 and 5 from?

[Star Strider]

Those are simply the independent variable limits I (abitrarily) set.

Experiment to get the result you want, since using your ‘c’ equation keeps producing NaN for me, so nothing plots.

Use an anonymous function representation to code it:

c = @(x,t) (Co./(sqrt(4*pi*D*t1))) .* exp(-((x-xo).^2)./(4*D*t));

then provide an appropriate range of values for the arguments.

Stopping here.

[elle morey]

how do i plot thatthen? i cant just use plot (c)can i?

[Star Strider]

No.

For a 3D plot (for a function with two arguments) use one of the surface plot functions.

t1=0;
t2=600;
t3=1200;
t4=1800;
t5=2400;
t6=3000;
t7=3600;
D=5e-9;
Co=1;
xo = 0;

c = @(x,t) (Co./(sqrt(4*pi*D*t1))) .* exp(-((x-xo).^2)./(4*D*t));

figure
fsurf(c, [1  10    0  10])

[X,T] = ndgrid(-5:01:5, 0.1:10);

figure
mesh(X, T, c(X,T))
grid on

This runs without error, however it doesn’t plot anything since all the elements of the matrix that ‘c’ produces are NaN.

You need to resolve that problem, so something shows up on the plot. I have no idea what you’re doing, so I can’t help you with that.