Why are there gaps in some of my plots?

Hello

I'm plotting a simple equation that seems to be producing the plot I want but is not displaying a continuous line. Its plotting as some kind of discontinuous step function, whereas, I would it to plot the step as a continuos line. I've tried changing the discretization of y, but that doesn't seem to help. Any other thoughts or suggestions would be greatly appreciated. Thanks in advance!

Here is a simplified version of my code:

x2=0;
D=1.003807*10^-7; 
u=0.0077;
y=-0.11:0.0001:0.11;

C=(1/2).*(1+erf(y./(sqrt(4*D*x2/u))));

figure
plot(C,y)

Answer 1

[per isakson]

Are there NaN in either C or y? Try

    any( isnan( C ) )
    any( isnan( y ) )

[Tanaya]

>> any( isnan( C ) )
    any( isnan( y ) )

ans =

       1

ans =

       0

Good call. Any ideas on how I can get around this?

[Matt Kindig]

Since x2=0, the sqrt() term will always be zero, so the y./sqrt() term will always yield Inf. You will notice that your C is always 0, 1, or NaN. Is this the intended result?

[Tanaya]

I used an even discretization value and started from an odd number so it never solves at zero! Thanks for pointing out the NaN.

Answer 2

[Matt Fig]

You have nans in your data because of this:

x2=0;
D=1.003807*10^-7; 
u=0.0077;
y=-0.11:0.0001:0.11;
T = sqrt(4*D*x2/u);  % Look at this one!
unique(T)  % You are dividing by zero in V
V = y./(T);  %  Look at this!
unique(V)
C=(1/2).*(1+erf(V));

.

.

So, why is T all zeros? Look at x2....