On Feb 8, 1:18�am, Tim Wescott <t...@seemywebsite.please> wrote:
> I want to say "a system is to a signal as a function is to a variable".
> Indeed, I'm pretty sure that when you've gotten fully spun off into
> Hilbert spaces and other esoteric stuff (which I can't say that I fully
> understand), the above statement is pretty close if not entirely true.
>
> But before I go and say it publicly in a seminar, I want to pass it by
> you sharks (uh, folks) and see if anyone has any strong objections that
> brush up close enough to real practice to make me want to change what I'm
> saying.
>
> --
> Tim Wescott
> Control system and signal processing consultingwww.wescottdesign.com
I don't know if this is a good analogy... but.. how does this analogy
help with the understanding of a system and signals?
Reply by robert bristow-johnson●February 9, 20122012-02-09
On 2/9/12 10:31 AM, Clay wrote:
>
> I hope you know I was teasing.
sure, i was too. (but it wasn't my intention to mistype tract. and in
the past, i once typed "baited breath", which created a silly side
discussion. sometimes i type phonetically.)
use to be i coodnt even spel enjunear. now i are one.
> But "GI track" made me immediately
> think of a soldier's footprints.
that's a connection i wouldn't have make.
errr *made*.
--
r b-j rbj@audioimagination.com
"Imagination is more important than knowledge."
Reply by Clay●February 9, 20122012-02-09
On Feb 8, 1:51�pm, robert bristow-johnson <r...@audioimagination.com>
wrote:
> On 2/8/12 12:18 PM, Clay wrote:
>
> > On Feb 8, 12:12 pm, robert bristow-johnson<r...@audioimagination.com>
> > wrote:
>
> >> ... a GI track is to a taco.
>
> > Did you mean footprints or tract? The difference is alimentary ;-)
>
> i dunno, Clay. �you tell me.
>
> waiting with baited breath.
>
> --
>
> r b-j � � � � � � � � �r...@audioimagination.com
>
> "Imagination is more important than knowledge."
I hope you know I was teasing. But "GI track" made me immediately
think of a soldier's footprints. I guess I spend too much time outside
watching wildlife and studying their prints and other things they
leave behind.
Clay
Reply by stan●February 9, 20122012-02-09
glen herrmannsfeldt wrote:
> davew <david.wooff@gmail.com> wrote:
>
> (snip)
>> They may nit pit. Doesn't a function have only one output?
>> A system could have many outputs.
My initial reaction was to say the statement was fine, but in the back
of my mind this was the point that caused me to hesitate
endorsement. If I were sitting in the room, this would occur to me but
I wouldn't consider it important enough to bring up and I don't think
it significantly hurts the presentation.
FWIW I don't recall ever seeing any definition or explanation that
didn't feel somehow incomplete or flawed.
> I believe that isn't quite right. You can, for example, have
> a vector valued function. Say, for example, velocity as a
> function of time. The important thing about such a function is
> that its value depends on its argument, not on, for example,
> the history of its argument.
I hadn't considered this before but you got me thinking. My memory is
that the important thing about function was mapping; input to single
(possibly vector) output. There was no mention that state information
was disallowed. Anyone know a reference for a definitive mathematical
answer?
Given the thread context, I see Glen's point but my curiosity started
twitching and my "within reach" reference stuff seems to be unhelpful.
Besides there's been no one roughed up yet, and since I've got some
kind of intestinal thing going on I couldn't really feel much worse :)
Reply by glen herrmannsfeldt●February 8, 20122012-02-08
davew <david.wooff@gmail.com> wrote:
(snip)
> They may nit pit. Doesn't a function have only one output?
> A system could have many outputs.
I believe that isn't quite right. You can, for example, have
a vector valued function. Say, for example, velocity as a
function of time. The important thing about such a function is
that its value depends on its argument, not on, for example,
the history of its argument.
Operators, such as the derivative or integration operator,
depend on more than just the value of their operand.
The output of a filter, analog or digital, depends on its
input and, usually, on previous values of its input.
Conveniently, many analog filters can be expressed in terms
of derivatives and integrals, and digital filters in terms
of differences and sums.
-- glen
Reply by davew●February 8, 20122012-02-08
On Feb 8, 6:18�am, Tim Wescott <t...@seemywebsite.please> wrote:
> I want to say "a system is to a signal as a function is to a variable".
> Indeed, I'm pretty sure that when you've gotten fully spun off into
> Hilbert spaces and other esoteric stuff (which I can't say that I fully
> understand), the above statement is pretty close if not entirely true.
>
> But before I go and say it publicly in a seminar, I want to pass it by
> you sharks (uh, folks) and see if anyone has any strong objections that
> brush up close enough to real practice to make me want to change what I'm
> saying.
>
> --
> Tim Wescott
> Control system and signal processing consultingwww.wescottdesign.com
They may nit pit. Doesn't a function have only one output? A system
could have many outputs.
Reply by Eric Jacobsen●February 8, 20122012-02-08
On Wed, 08 Feb 2012 00:18:12 -0600, Tim Wescott
<tim@seemywebsite.please> wrote:
>I want to say "a system is to a signal as a function is to a variable".
>Indeed, I'm pretty sure that when you've gotten fully spun off into
>Hilbert spaces and other esoteric stuff (which I can't say that I fully
>understand), the above statement is pretty close if not entirely true.
>
>But before I go and say it publicly in a seminar, I want to pass it by
>you sharks (uh, folks) and see if anyone has any strong objections that
>brush up close enough to real practice to make me want to change what I'm
>saying.
>
>--
>Tim Wescott
>Control system and signal processing consulting
>www.wescottdesign.com
Sounds okay to me, and I think it makes the point, but I'm not
excessively anal about being rigid with terminology. No matter what
you say some nit can pick at it, so take that FWIW.
Eric Jacobsen
Anchor Hill Communications
www.anchorhill.com
Reply by dvsarwate●February 8, 20122012-02-08
On Feb 8, 1:51�pm, robert bristow-johnson <r...@audioimagination.com>
wrote:
>
> waiting with baited breath.
>
Well, if rb-j has been eating tacos, he is certainly waiting
with baited breath for the onslaught to begin. The only
other time I have read this variant spelling is in a review
of a Warner Brothers cartoon where Sylvester is described
as having eaten cheese and waiting with baited breath near
a mouse hole for Speedy Gonzalez to appear.
Reply by Greg Berchin●February 8, 20122012-02-08
On Wed, 08 Feb 2012 13:13:05 -0600, Tim Wescott <tim@seemywebsite.com> wrote:
>And -- why these ad homonym attacks on RBJ?
Because ad hominem attacks just don't sound the same.
Reply by Tim Wescott●February 8, 20122012-02-08
On Wed, 08 Feb 2012 13:51:08 -0500, robert bristow-johnson wrote:
> On 2/8/12 12:18 PM, Clay wrote:
>> On Feb 8, 12:12 pm, robert bristow-johnson<r...@audioimagination.com>
>> wrote:
>>
>>> ... a GI track is to a taco.
>>
>> Did you mean footprints or tract? The difference is alimentary ;-)
>>
>>
> i dunno, Clay. you tell me.
>
> waiting with baited breath.
Did you mean 'equipped with bait', or bated, as in 'held, temporarily
stopped'?
And -- why these ad homonym attacks on RBJ?
--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com