My vote it that there is an excessive amount of ego bolstering going on.
Nothing more nothing less.
73
Gary K4FMX
MorgusMagnificen@aol.com wrote:
> Okay, I sincerely apologize for the aggressive broadside. I am just sick and
> tired of hearing all of the distortions of theoretical science and
> engineering that I hear EVERYWHERE . I hoped this group would have a little
> more understanding of it. If your world ends at the 4th significant figure,
> fine for you. For many others, the action doesn't even begin until the 6th -
> or 10th.
>
> One statement by you and others ( in some of those OTHER armchairs) regards
> the term 'computer modelling'. There is somewhat of a semantic problem here,
> as follows. The computer models which we use are EXACT, precise physical
> devices whose electronic equations we can write precisely. We can then apply
> them in circuits and solve the circuit equations to any desired degree of
> accuracy. In the limit (this is a profound mathematical statement, which
> forms the basis of all numerical computation algorithms) these solutions
> converge to the exact answer (if the algorithm designer has not screwed up!).
>
> The approximation comes in when we attempt to apply this exact model to a
> practical circuit. Again, the degree of agreement between the two is limited
> by our ability to measure the real-world components, which we all know has
> practical as well as theoretical limits. So it is not the modelling process
> which is 'inexact'. The error comes from our measurment limits, which we
> know, control, and can accurately predict.
>
> The laws of physics themselves are models. I posed the very relavent question
> "is the formula R=E/I an exact model" and no one wants to take a stand on
> that, the most basic of all of our electrical 'laws'. That we can approach
> exactness only in the limit sense does not make it any less useful to us.
>
> I want to close this (although I am sure you would like to conrtinue to hear
> me rant) by going back to where it began, and show how all of those who have
> argued against me have badly distorted the issue. It started when Jeff posted
> a very simple solution to a somewhat complex problem - the calculation of
> filter capacitance in a PS. I was, like others, initially suspicious of his
> results but I wanted to check it out as accurately as possible before
> attacking his work. To do so, I made the most accurate calculation I could of
> the same problem, so that if I were to raise a complaint, no one could accuse
> me of basing it on an inexact calculation (i.e. an approximation, with which
> the older power supply literature is filled .) So by comparison, my
> calculations were so precise (let's say they produced results accurate to
> .01%) that they were effectively exact in comparison to older data. To most
> engineers I know, that constitutes an exact calculation. (What you may not
> realize is that this 'old' data which I always refer to was based on highly
> approximated models - with our modern computers we do not have to severely
> approximate our models.)
>
> Does it really change anything if I change the wording to read 'highly
> precise' calculations instead of 'exact'? Would it convey any more or less
> useful information to you? Would it make any difference when you finally get
> back to your workshop to build your amp, for which you will be doing well to
> get a filter cap that is within 10% of the predicted EXACT value?
>
> I would like to ask for a polling by everyone reading this (if you are still
> awake) on the following: Does the fact that my calculations were terminated
> at an accuracy of .01%, as opposed to the known errors of 10% or greater in
> old data, mean that my calculations are not exact? And if not, how precise
> would I have to make them in order to qualify as a standard against which to
> measure simple approximated calculations, such as Jeff's? Does it bother you
> that I use the word 'exact' in the context of "high-accuracy, so high that
> its estimated error is too low to be of any concern" ?.
>
> Eric K8LV
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