Matlab plotting?

Question

This Matlab code here is supposed to plot the values stored in the vector X and Y which are already filled by the user, the problem here is : when you click on complex and real poles, the plotting results the right points, while when entering only real poles, the output is weird. It's like the x-axis is on the y-axis, and I don't know what is exactly on the horizontal axis.

axis([-10,10,-10,10])
grid
[x,y] = ginput 

subplot(2,2,1)
axis([-10,10,-10,10])
grid

subplot(2,2,2)
axis([-10,10,-10,10])
hold all
grid


x = round (x)
y = round (y)

if( y > 0.5 | y < 0.5)
r1 = x + i*y
r2 = conj(r1)

plot (r1,'*')
hold all 
plot (r2,'*')

else

plot (x,y)

end

I've read through this a few times and I'm not sure what you're asking. Can you please clarify your question? — slayton
idk what you're trying to do here, but you realize that 'if( y > 0.5 | y < 0.5)' is only false for y=0.5, right? — jerad
to add to jerad's comment y = 0.5 will never occur because you round off the values of x and y. — mythealias
@slayton : sorry for the misunderstanding, I hope I have made it clearer in my answer below. — Nour

PearsonArtPhoto PearsonArtPhoto · Accepted Answer · 2012-12-01T11:49:20

I'm not 100% sure what you are saying, but I believe you problem is in the if statement as shown below. Specifically, you can never enter the first clause unless y=.5, which is unlikely. I suspect you wanted abs(y)<0.5, to look between [-0.5 0.5]. Secondly, your two plots don't match each other, the first plots complex numbers, and the second x and y values. That just doesn't seem right, but I'm not certain what you are trying to do, so I don't know how to fix it.

if( y > 0.5 | y < 0.5)

    r1 = x + i*y
    r2 = conj(r1)

    plot (r1,'*')
    hold all 
    plot (r2,'*')

else

    plot (x,y)

end

Matlab plotting?

2 Answers