How to graph irrational functions

I'm trying to graph this equation: k = (s-2)/(-s^2-s+6), but I keep getting errors like "Error using ^ Inputs must be a scalar and a square matrix. To compute elementwise POWER, use POWER (.^) instead."

How do I graph this? Below is the code I'm using

k = [0,50];
s = [-3, 2];
k = (s-2)/(-s^2-s+6);
plot (k,s)

Answer 1

[Walter Roberson]

k = @(s) (s-2) ./ (-s.^2-s+6);
s = linspace(-3, 2);
kv = k(s);
plot(s, kv)

Answer 2

[Chad Greene]

You can fix that error by including the . when you multiply or compute the exponent:

k = (s-2)./(-s.^2-s+6);

But nothing will show up, because for the values you provided you're dividing by zero.

Answer 3

[Roger Stafford]

I think what you are trying to do is this (it’s just a guess.)

s = linspace(-3,2);
k = -1./(s+3);
plot(s,k)

Note: The fraction (s-2)/(-s^2-s+6) simplifies to -1/(s+3).

Note 2: You will get an infinite value at s = -3 so that point will not appear on the plot.

Note 3: The function you describe is a rational, not an irrational, function!

Answer 4

[Brendan Nikola]

That's it! Thank-you! I hvae a follow up question. If I wanted to include the jw imaginary axis, how what I write that?

[Chad Greene]

You're unlikely to get an answer to any question if the question is written in the answer space of your own question. I recommend starting a new thread for each new question.