Re: Impulse Fumction using UnitStep???
- To: mathgroup at smc.vnet.net
- Subject: [mg17566] Re: Impulse Fumction using UnitStep???
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Mon, 17 May 1999 02:14:23 -0400
- Organization: Mathematics & Statistics, Univ. of Mass./Amherst
- References: <7hge6f$4dd@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Define it just like you said:
f[t_] := 0
f[0] = 1;
This adds two rules to Mathematica's rule database: the particular one
for f[0], and the more general one -- used whenever the particular one
does not apply, that is for all t other than 0.
Example:
In: Table[f[t], {t, -2, 2, 1/2}
Out: {0,0,0,0,1,0,0,0,0}
Caution (exact integer 0 is not same as floating-point, approximate real
number 0. ):
In: Table[f[t], {t, 02, 2, 0.5}]
Out: {0,0,0,0,0,0,0,0,0}
Fix:
In: f[0.] = 1;
In: Table[f[t], {t, 02, 2, 0.5}]
Out: {0,0,0,0,1,0,0,0,0}
heiffer wrote:
>
> hi,
>
> i am taking a control systems course at university and i am trying to
> evaluate an impulse function [ f[t]=0 except at f[0]=1 for, say a range
> of -5 top 5 ].
>
> i have managed to get the step and ramp functions going using the
> UnitStep function, but i could not work out the Impulse function. Any
> help would be appreciated.
>
> regards,
>
> heath
--
Murray Eisenberg murray at math.umass.edu
Mathematics & Statistics Dept. phone 413 549-1020 (H)
Univ. of Massachusetts 413 545-2859 (W)
Amherst, MA 01003-4515