Sometimes my 2-D plots won't show up.

My 2-D plots will sometimes not plot. Sometimes they work, and sometimes they won't plot, and I can't figure out why. I'm very new to Matlab so it's probably something basic that i'm not doing correctly. The "New Figure option" in the Plots menu is checked.

[Torsten]

If it's a problem with your code, we cannot help since you didn't include it.

If it's a problem with your graphics card, we cannot help anyhow.

[Torsten]

@John comment moved here:

Here's the code I'm using: I got no errors or warnings (green check mark). How can i check if it's a graphic card issue? Also I'm connecting to matlab through a remote server since I don't have the software on my computer. I'm new to matlab so any help is much appreciated!

Fb0=0.5465;
Na0=1544;
K=8.33*10^-5;
x=0:36000:360000;
y=K*(1+(Fb0*x/Na0))-realsqrt(((K*(1+Fb0*x/Na0))^2)-4*(K-1)*K*Fb0*x/Na0)/2*(K-1);
plot(x,y);
drawnow;

[Torsten]

Replace

y=K*(1+(Fb0*x/Na0))-realsqrt(((K*(1+Fb0*x/Na0))^2)-4*(K-1)*K*Fb0*x/Na0)/2*(K-1);

by

y=K*(1+(Fb0*x/Na0))-realsqrt(((K*(1+Fb0*x/Na0)).^2)-4*(K-1)*K*Fb0*x/Na0)/2*(K-1);

[John]

Thank you so much! That worked! I appreciate explaining why it didn't work before. This is a great learning and great value!

Answer 1

[Star Strider]

Normally, that sort of problem is caused by using matrix division (/) instead of element-wise array division (./) however the ‘x’ vector does not appear in the denominator, so that is not the problem here. The only problem I found is that you need to use element-wise exponentiation (.^ instead of ^):

y=K*(1+(Fb0*x/Na0))-realsqrt(((K*(1+Fb0*x/Na0)).^2)-4*(K-1)*K*Fb0*x/Na0)/2*(K-1)

↑ ← HERE

however that should throw an error.

With that change, I don’t see any problems —

Fb0=0.5465;
Na0=1544;
K=8.33*10^-5;
x=0:36000:360000;
y=K*(1+(Fb0*x/Na0))-realsqrt(((K*(1+Fb0*x/Na0)).^2)-4*(K-1)*K*Fb0*x/Na0)/2*(K-1)

y = 1×11

0.0001 0.0337 0.0483 0.0597 0.0695 0.0783 0.0863 0.0938 0.1008 0.1075 0.1138

plot(x,y);

The drawnow function us usually used with animated plots. Since it doesn’t appear to be appropriate here, I don’t use it.

.