Conversion to double from tf is not possible

Hi I am new in Matlab...... i am working on suspension system..so I need to filter my acceleration found from random input. I am using 2nd order butter worth filter. Here is the code i tried....

ts = 0.001; t = 0:ts:10; n=2; Fs=1000; w=.10; z=.7;(the value of parameter)

num=[1/w^2];
den=[1/w^2 2*z*w 1];
sys=tf(num,den);
filter= sys*y3;% (here y3 means the equation of the acceleration found after input random track input)

Now then I tried to plot the result...like this way...

subplot(2,1,1), plot(t,y3),title('passive_ acceleration')
subplot(2,1,2), plot(t,filter), title('filtered_ acceleration')

Then it shows that 'Conversion to double from tf is not possible'....Please help me...I am stuck here badly.....

Answer 1

[Walter Roberson]

You should be using the filter() call to filter your data; see http://www.mathworks.com/help/signal/ug/filter-implementation-and-analysis.html#f1-821

It is not advisable to use "filter" as the name of a variable, as that will interfere with calling the filter() function.

[md]

@ Walter Roberson, Thanks boss....its working....