Ask Your Question

Are there transfer function, state space, and bode plots?

asked 2014-08-20 08:06:30 -0600

Rongcui Dong gravatar image

I am looking for something like tf(), ss(), and bode() in control package of Octave, but I don't see them in sage. Are there any equivalents?

edit retag flag offensive close merge delete


las bases teóricas-matematicas son la equivalencia que buscas

luisratia gravatar imageluisratia ( 2014-08-20 14:29:42 -0600 )edit

I'm sorry, but I can read nothing other than English and Chinese...

Rongcui Dong gravatar imageRongcui Dong ( 2014-08-20 16:58:33 -0600 )edit

4 answers

Sort by » oldest newest most voted

answered 2014-08-20 10:17:49 -0600

luisratia gravatar image

updated 2014-08-20 12:23:42 -0600

En Sage, la graficas son exactas y las unidades son en decibelios en el eje de salida y radianes en la grafica de magnitud, en la fase son grados en el eje y y radianes en el eje x, en las dos graficas el eje x es semilogaritmico. Yo comparo estas con los libros de control automatico y los resultados son totalmente compatibles.

Edit: translation. In Sage, the graphics are exact and the units are decibels on the output axis and radians for the magnitude; in the phase, degrees in the $y$-axis and radians in the $x$-axis; in both graphics the $x$-axis is semilogarithmic. I compare these with books on automatic control and the results are fully compatible.

edit flag offensive delete link more


Sorry, I can't read this...

Rongcui Dong gravatar imageRongcui Dong ( 2014-08-20 10:27:26 -0600 )edit

I know how to plot if I type in the function manually. I am just trying to find a way so that I don't need to type lots of 20*log(abs(H),10) or H.subs(s=I*omega) things, they are all repetitive.

Rongcui Dong gravatar imageRongcui Dong ( 2014-08-20 13:18:12 -0600 )edit

answered 2014-08-20 14:06:16 -0600

luisratia gravatar image

pues no se si son repetitivas, se define G(s) una ves y luego a partir de esa funcion se obtienen las graficas. Una solución es crear una funcion sage y pasarle a G(s) como argumento, esta funcion sage retorna las graficas de bode y nyquist, o grafica polar, tambien puedes obteber la de Nichols.

edit flag offensive delete link more

answered 2014-08-20 13:20:07 -0600

Rongcui Dong gravatar image

updated 2014-08-21 17:17:16 -0600

There seems to be something like that in numpy/scipy, I will check that out.

UPDATE: Now I use Sage/Sympy to derive the symbolic function, and convert the numerator and denominator to coefficients of polynomials, and create LTI systems in Scipy to use functions like LTI.bode(), signal.convolve(), etc. Also, I really can't read most of your answers.

edit flag offensive delete link more

answered 2014-08-20 12:17:50 -0600

Luis Ratia has made some Sage notebook worksheets available: Bode plots, and just recently posted about it on the sage-support and sage-notebook Google groups.

edit flag offensive delete link more


Thanks, but I know how to do that. I am just not sure if there is an automatic way to help me do the s=I*omega and 20*log(abs(H),10) etc.

Rongcui Dong gravatar imageRongcui Dong ( 2014-08-20 13:19:38 -0600 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower


Asked: 2014-08-20 08:06:30 -0600

Seen: 1,036 times

Last updated: Aug 21 '14