producing the magnitude of the butterworth graph

Question

u-will-neva-no 2012-1-22

Hello everyone, I am trying to write some matlab code to show the magnitude of the butterworth equation of order 2.

The equation is: T(s) = 1/(s^2 + sqrt(2) +1.

Here is my matlab code: [code] %magnitude of butterworth filter characteristic frequency = 0.1:0.1:100;

w = 2*pi*frequency; s = j*w; butterworth = 1./(s.^2 + sqrt(2).*s +1); mag = abs(butterworth); plot(semilogx(freq),mag); [/code]

I want a range of frequencies from 0.1 to 100 rad/s and used the semilogx() function so that the x axis would have powers such as 10^0, 10^1 etc...

The graph is not correct however and I can not see what is wrong with it.

Thank you in advance

Answer 1

bym 2012-1-22

replace your plot(...) with

semilogx(frequency,mag);

semilog does its own plotting

u-will-neva-no 2012-1-23

Thank you!