Difficulties in understanding e^(-jwt)



It is you that is posting hogwash AND being very rude about it you jerk off.
Blair
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I an never rude, nor have I ever used these International Fora to broadcast hogwash.
It seems almost inconceivable that the contributors to the gangrenous degeneration that is alt.electrical.engineering would have such a primitive understanding of the level of arithmatic required to pass an examination written for 6 year olds!
I append some text to disambiguate.
-----ooooo-----
Copyright 1999 G.A.Evans. All Rights Reserved.
OK, you're still with me - good! I am pleased that you are determined to make the effort to improve yourselves. I was a bit worried that my audience would consist of only negative CB whingers, who never get anywhere, and who gripe persistently that we Radio Hams never do anything to encourage newcomers. In fact, such is the bigotry of such whingers in this NG, that I half expected them to interpret my opening comments in Lesson 1 as a polemic against CBers. How wrong can you be!
Where do we go from here? OK. I'm going to take you through some essential ideas in maths, and then I'm going to leave the maths behind for a while and start talking about electrical matters. (It's electricity that matters for Radio Hams!) My first topic on electrical matters will be "Energy"; this should give you advanced notice to enable you to think about what energy means to you.
For the moment, though, let's get back to the maths.
Some of the topics I am going to cover may seem to you to be far too simple, but let's get the foundations secure before we build the walls. The topics I have selected come from my experience as a part-time tutor in adult education, dealing with the common problems that my students come up with.
Here's the road map :- Addition, Multiplication, Finish Off Addition, Subtraction, Negative Numbers, Division, Fractions And Decimals, Brackets. Algebraic Puzzles.
At this point, you will have enough under your belt to solve electrical formulae, I will stress time and time again that THERE IS NOTHING NEW IN MATHS - most of what you will come across will be a different way of writing down something that you already know. The different way is a shorthand to make life easy. But remember! If at any time you are confused by the new short-hands, you can always go back and work in the older, simpler ways, (although it might take you longer, you'll still get the correct answer!)
ADDITION
Suppose that you've got three eggs (and continuing my pun of "X's" for eggs, you will have XXX.) Someone now gives you another five XXXXX. How many have you got? Well, you put your three, XXX, next to the new five, XXXXX giving you XXXXXXXX, and you count them again. This is the simple rule for addition. You had three, you add another five, giving you eight. You don't need to understand how to do adding, because after putting them together, you can count them again from scratch.
OK. Suppose that your weekly income is 200, and you get a raise of 37 pounds per week, the same principle applies - put down 200 ticks, then write down a further 37, and count them all from scratch - you're doing addition.....
XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX XXXXXXX
This soon gets tedious, so let's devise a shorthand to make life easier - but remember! You don't HAVE to use the shorthand, because it's just another way of writing down something that you already know - you can carry on putting down two lots of ticks next to each other, and count them all again from scratch.
The short-hand is "5 + 3", where the "+" is known as a "Plus Sign". When you see this Plus Sign ("+"), it means take the number on the left side, and write down that many ticks. Then take the number on the right side, and write down THAT many ticks, right next to the original group of ticks. Then count how many ticks you've got altogether.
So, let's recap... you can see in the example TWO short hands, firstly the use of "5" instead of "XXXXX", and then the use of "+" to read as the instruction to do an addition. OK. I bet you've never seen that presented like that before, but you see, even addition, which you did right in the early days at school, is a convenient way OF WRITING DOWN SOMETHING ELSE WHICH YOU ALREADY KNEW ABOUT.
Now, whether you do 5 + 3 :- XXXXX then XXX to give XXXXXXXX or 3 + 5 :- XXX then XXXXX to give XXXXXXXX you get the same result. This effect is known in the trade as "Commutativeness", which means "switching around". The word has the same origin as the "commutator" in an electric motor which "switches around" the coils in the armature.
OK, in the early days, one concept per lesson is more than enough. I need to digress into multiplication in the next lesson, before I can finish with addition.
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Nathan Hull G7KUJ posting as, "+7IiMjEePDrUlHMcutxEQw.user.aioe.org" at least acknowledges my copyright.
One is forced to ask, however, what it is that Nathan Hull G7KUJ hopes to achieve by flooding this thread with evidence of his mentally deficient obsession? Has he no life of worth of his own?
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I'm on holiday, and haven't been on the web for the last few days... What have you been upto? Oh yes, countless posts of utter drivel, as per norm. Now run along and have another Special Brew. Have you trimmed your front hedge yet?
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on 24/08/2007 19:43 huLLy said the following:

Should he put hedge trimming on his CV?
--
;-)
73 de Frank Turner-Smith G3VKI - mine's a pint.
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8 years later and hes still working on lesson 2...

--
Posted via a free Usenet account from http://www.teranews.com


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As indeed it is not.
You can certainly evaluate a quotient by multiplying by unity (a unity that is the quotient of the original denominator over itself), but evaluating the quotient by the action of multiplication is not the action of division.
How would you evaluate (253 + 16j) / (4 +3j) by a dividing process? Would you divide the 253 by the 4 in the first instance or the 16j by the 3j?
Division is only valid for vector quantities when those vectors are related by simple colinearity.
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Oops!
The _COMPLEX CONJUGATE_ of the original denominator over itself!
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----------------------------

------------ Read again- the interpretation that I said was wrong (and appeared to be based on real numbers) is that e^-jwt decreases (in magnitude as I assumed -otherwise it makes even less sense.) as t increases. However, e^jwt is strictly a mathematical concept which happens to be useful in many situations (particularly in electric circuit theory) but does't actually directly describe something physically real.
--

Don Kelly snipped-for-privacy@shawcross.ca
remove the X to answer
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Brian Reay take note!
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But the whole idea of directed numbers is that the direction changes when you pass through zero, and you then _INCREASE_!! Brian, please think about what you type in your desperation to divert attention away from your own error!
You're digging a bigger hole for yourself in attempting to divert a technical discussion into one of a slanging match. That you try to do this shows to a greater and greater extent the error in your original publication. What is of concern is that you are a teacher of mathematics, the truth basis of all science and yet here you are, not only spouting nonsense, but also seeking to defend nonsense!

As I said above, you're digging a bigger hole for yourself in attempting to divert a technical discussion into one of a slanging match.
Brian, you are pathologically incapable of recognising or even admitting, when you are in error, to the extent that you even removed the cross-post to alt.engineering.electrical to prevent those in the know witnessing your further squirming.
Did you not notice that Don Kelly's remarks,.....
"Read again- the interpretation that I said was wrong (and appeared to be based on real numbers) is that e^-jwt decreases (in magnitude as I assumed -otherwise it makes even less sense.) as t increases.".....
referred only to _YOUR_ assertions and not to anything that I had posted. It referred to _YOUR_ assertions and not to any interpretation that I had put on them.
Give up now while you're still on a losing streak!
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That doesn't make any sense, which wouldn't matter except for you being a schoolteacher. Are you claiming that you measure angles using something other than real numbers?
Brian! Stop and think what you type!
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which was

Indeed. However it was the blatant misunderstanding, "a value that decreases as t increasing" that I was discussing.
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