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.
A System is to a Signal as...
Started by ●February 8, 2012
Reply by ●February 8, 20122012-02-08
Reply by ●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 ●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.comSounds 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 ●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.comThey may nit pit. Doesn't a function have only one output? A system could have many outputs.
Reply by ●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 ●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 ●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 ●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 ●February 9, 20122012-02-09
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.comI don't know if this is a good analogy... but.. how does this analogy help with the understanding of a system and signals?
