COMPGROUPS.NET | Search | Post Question | Groups | Stream | About | Register

### How to create a unit step function??

• Email
• Follow

```I need to plot the following: x1(t)= tu(t)-tu(t-1)

this is what i've done so far to deal with the u(t-1) part:
(disregard the numbers here as i've yet to define my interval)
u=zeros(11,1);
u(6:end)=1;

this gives me a column with the first five rows being 0 and the rest 1

i thought i could multiply this with t to get the desired effect, but understandably i get an 11x11 matrix and i can't really plot this vs time

```
 0
Reply Miguel 1/12/2011 5:36:05 AM

See related articles to this posting

```"Miguel Bustelo" wrote in message <igjek5\$3jc\$1@fred.mathworks.com>...
> I need to plot the following: x1(t)= tu(t)-tu(t-1)
>
> this is what i've done so far to deal with the u(t-1) part:
> (disregard the numbers here as i've yet to define my interval)
> u=zeros(11,1);
> u(6:end)=1;
>
> this gives me a column with the first five rows being 0 and the rest 1
>
> i thought i could multiply this with t to get the desired effect, but understandably i get an 11x11 matrix and i can't really plot this vs time
>
>

http://www.mathworks.com/help/toolbox/control/ref/lsim.html
```
 0
Reply Husam 1/12/2011 5:54:05 AM

```"Husam Aldahiyat" wrote in message <igjfls\$a57\$1@fred.mathworks.com>...
> "Miguel Bustelo" wrote in message <igjek5\$3jc\$1@fred.mathworks.com>...
> > I need to plot the following: x1(t)= tu(t)-tu(t-1)
> >
> > this is what i've done so far to deal with the u(t-1) part:
> > (disregard the numbers here as i've yet to define my interval)
> > u=zeros(11,1);
> > u(6:end)=1;
> >
> > this gives me a column with the first five rows being 0 and the rest 1
> >
> > i thought i could multiply this with t to get the desired effect, but understandably i get an 11x11 matrix and i can't really plot this vs time
> >
> >
>
> http://www.mathworks.com/help/toolbox/control/ref/lsim.html

lsim(sys,u,t)
this actually worked:
laplace of t = 1/s^2 so:

H=tf([10],[1 0 0])

Transfer function:
10
---
s^2

>> t=0:.01:10;
>> u=zeros(100,1);
>> u=zeros(1000,1);
>> u(100:end)=1;
>> lsim(H,u,t)
??? Error using ==> lti.lsim at 117
When simulating the response to a specific input signal, the input data U
must be a matrix with as many rows as samples in the time vector T, and as
many columns as input channels.

>> u=zeros(1001,1);
>> u(101:end)=1;
>> lsim(H,u,t)
>>

and i got the plot
--------
but thats only when i take that last part of the equation x1(t)= tu(t)-tu(t-1)
how do i plot for all of that^
....and i can't have MATLAB simply directly plot this because i need x1(t) to be defined so i can convolute it with another function.
```
 0
Reply Miguel 1/12/2011 6:32:04 AM

```"Husam Aldahiyat" wrote in message <igjfls\$a57\$1@fred.mathworks.com>...
> "Miguel Bustelo" wrote in message <igjek5\$3jc\$1@fred.mathworks.com>...
> > I need to plot the following: x1(t)= tu(t)-tu(t-1)
> >
> > this is what i've done so far to deal with the u(t-1) part:
> > (disregard the numbers here as i've yet to define my interval)
> > u=zeros(11,1);
> > u(6:end)=1;
> >
> > this gives me a column with the first five rows being 0 and the rest 1
> >
> > i thought i could multiply this with t to get the desired effect, but understandably i get an 11x11 matrix and i can't really plot this vs time
> >
> >
>
> http://www.mathworks.com/help/toolbox/control/ref/lsim.html

i also don't have that heaviside function available
```
 0
Reply Miguel 1/12/2011 6:42:05 AM

3 Replies
2377 Views

Similar Articles

12/1/2013 3:31:17 AM
page loaded in 637495 ms -1