Re: Wireless Power Nearly There

There were no Floppy drives when Jim went to school. The rich kids had slide rules. The rest were still using their family's abacus. The few computers in existence used punched cards and vacuum tubes. OTOH, I don't believe his claim that he had a pet dinosaur. ;-)

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There are two kinds of people on this earth: The crazy, and the insane. The first sign of insanity is denying that you're crazy.

'ey, krw.

Yes. She was about 1/3 through the book; then Dad got a lot sicker. She'll go back to studying when he's dead or in a rest home.

JMF's cousin-in-law was going to college (after raising her kids) to get a teacher's degree. One of the requirements was a year of algebra. She was petrified of it. When she was in high school, her algebra teacher (a male) made her stand up in front of the class while he told her for 15 minutes why she was too stupid to learn any algebra. She never took another math course.

So I sent her Schaum's algebra. She and her precocious son, I think he was 8, went through the book together at home. She aced her college algebra course and discovered she really like math.

At the same time, I also sent her Dr. Hawking's book which he wrote for the general public. I included a note saying that she didn't have to understand everything in order to read it. She read it. The next year, in her algebra class, the prof asked who had read the book. She was the only one and the prof noted that she was highly intelligent. Those were the two things necessary to get this woman to meet math and discover she liked it.

Yea, well. People who don't have money to waste learn very quickly how to do this kind of analysis.

How could I forget about compound interest and mortages? :-) Thanks.

/BAH

I figured that out after I sent the post :-).

Well, then I would have asked about the plumbing but they probably didn't have bathrooms. Aha! I could have asked about his prized glass gear he made in the labs.

Oh, that must have been a skunk.

/BAH

I also have another story. I and another lady were waiting in line at the book store. She said that she was about to sign up for Calculus 101 and was scared to death of it. I asked her if she had taken algebra; she had. I asked if she had liked algebra; she had, a lot. So I told her that calculus was a shorthand method of doing algebra.

I never saw her again so I don't know how she fared.

/BAH

/BAH

What fraction of the population does symbolic math manipulations in their real lives? My wife is a speech pathologist, and I assure you that she doesn't. I doubt that the average MD uses algebra. I'm certain that few electricians, cooks, car repair guys, office workers, or truck drivers do. If they learned it in school, they likely forgot it through disuse. I've certainly forgotten how to extract a square root manually, and I'm not sure I can still do long division.

Most people have some degree of instinct for quantities, summing lists, multiplying and dividing things. But they don't write equations in X and solve them.

Everybody should be exposed to a little algebra in school, and they should pursue it, and higher math, if they have the interest and aptitude. But if their brain doesn't work that way, it's a waste to try to pound it into them. We should recognize how incredibly different individuals can be.

John

Except this one is quite green.

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

Dukakis, asked to cite Obama's accomplishments, "Uh..Uh..Uh..Uh.."

Anyone who writes loop/nodal equations regularly, as I do, uses Algebra.

...Jim Thompson

In 1959 ?:-)

Nobody 'fessed up :)

...Jim Thompson

You have that backwards, the rich kids had a slave to operate the abacus... us poor folk had a "slip-stick" ;-)

...Jim Thompson

Only if they have one of those problems where supermarket offers are buy one get one free vs some other more complex multiproduct deal. These days so few people can add up without a calculator that insane numerical results go unchallenged. I see offers of pay more per unit price for the special offer sometimes as compared to some other equivalent size.

If the bar code says that a candy bar is a 20' long 10"x8" roofing timber they will happily process it as such at the checkout.

If you think you can get away with numerical futzing for everything no wonder you have such a big chip on your shoulder about programmers.

Try solving Keplers equation by numerical futzing and you will be well on your way to madness. It is deceptively simple to state:

M = E - e.sin(E)

Where 0 > a common symbolic language is a requirement in daily living

That is pretty bad. If you have ever solved a quadratic then you should be able to derive how to do square roots by hand pretty easily.

I agree that there is no point at all in pounding it into them.

But I do find it just a tadge annoying that it is so fashionable now to say "I am no good at maths" and still be considered well educated. The world is full of innumerate senior managers wrecking IT (and other) large projects through an inability to understand relatively simple abstract calculations.

Regards, Martin Brown

And what fraction of the population does loop/nodal equations?

John

ALL of us _important_ folk ;-)

...Jim Thompson

Last week we had a test-off for the best 32-bit integer square root, my Newton's iteration against R's paired-bit-shifter thing, which somehow does the root with no muls or divs. Mine won, mostly because our CPU has nice fast mul/div hardware, and his thing had too many loops. Mine's shorter too, 10 lines of assembly. R needs to extract the mean (DC) and RMS deviation (AC) components of a set of ADC samples using the algorithm that only crunches each sample once.

I started with a fixed seed of 200 and iterated 6 times. It would be better with a little logic to bracket the seed a little closer, although I doubt that an end test would be any better than the six loops. After six it tends to just dither anyhow.

I've been meaning to try square root by bitwise successive approximation, just for fun.

I'm not trashing algebra except when it becomes a mindless procedure pounded into unwilling students, like the classic manual square-root algorithm, which I never understood and can't remember.

I can usually guess a square root to within 5 per cent accuracy, sort of bracketing with a couple of cardinal points and mentally interpolating.

There's a big difference between having a deep gut feel for mathematics and rote learning of algorithmic procedures, like taking square roots. For one, the algorithms are soon forgotten if not often used. My math instincts are pretty good because I can visualize Fourier transforms and double integrations and modulation and sidebands and such, which is a whole different thing from doing the sterile math exercizes at the ends of chapters. I can always use a calculator, or write a Basic program, or look up a trig identity, or use Spice to do the number crunching.

There's too much teaching of uninterested students by uninterested teachers, so that the kids can pass a standard test and then forget. That sort of process crushes the talented kids who wouldn't forget if taught to truly understand and appreciate the math.

Life is an open-book exam.

Even a lot of engineering instructors dump a lot of math on a whiteboard, and crunch the solutions, and think they're done. There's no deep understanding there, just manipulation. It's funny (or sometimes sad) to see someone do a page or two of complex math which is, in the end, totally silly without their having any way or means to sanity check it.

John

Do they not teach simple harmonic motion these days at US high schools?

In the UK there was insane pre metrication ton, cwt, st, lb, oz etc arithmetic for primary school children and spherical trig for navigation at high school. Calculus was introduced at around age 14 and intgration by parts and trickier second order DEs at 16-18 (A'level). Physics used the pure mathematics as it was taught.

You could get away with 3 sig fig using a slide rule too.

Odd. A'level maths students in my day were expected to have a reasonable knowledge of calculus. AFAICT calculus is no longer taught at O'level in the UK. My university was pretty extreme, but they assumed knowledge of basic calculus and vectors. But I doubt if they can do that now.

ISTR Mathematics students spent most of the first term proving 0!=1.

What do you expect if you vote a moron in as president for 8 years??

Presumably the purpose of the test then is to make money for the testers? ETS only seem to be in it for the money.

They made a right Balls up of the UK SATs tests this year and lost the contract as a result. Hard to believe but the Minister for Education really is called Ed Balls.

Regards, Martin Brown

I never liked loop analysis... it's throwing the whole problem into one matrix-math basket. I prefer Thevenin reduction, so I can see all the intermediate steps and sanity check them along the way. But nowadays, if it's not fairly simple, I just Spice it. I don't use a slide rule or a book of log tables any more either.

I'd hazard that, of the 100 richest or most powerful people in the world, only a couple have ever done loop/nodal analysis.

John

Indeed! Many of my MIT exams were open-book. You still have to pretty much know all of the material, otherwise you can't look up stuff fast enough to finish in the allotted time.

"Sanity check" separates the real engineers from the hackers ;-)

...Jim Thompson

That's a non-sequitur. Did YOU graduate from Yale? Please DO cite YOUR academic accomplishments... for our amusement ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

Why are Europeons so ignorant? They think they know it all about the U.S.A. But never have bothered to visit

Nothing wrong with that. You don't have to throw all your loops into one basket though, either -- you can can do it in intermediate steps if you prefer.

If you're using well-known (to you) architectures, sure, you might as well SPICE it... but if you're doing something new, getting a symbolic expression for how your various inputs and outputs relate is a lot more valuable than just a graph or table.

I am all for, e.g., Phantom's approach of using a tool like Mathematica to actually *do* the algebra.

A better metric might be... of the 100 richest or most powerful people in the world, how many do loop/nodal analysis themselves *or are employing someone to do so for them?* After all, the first people you hire in a business are often those who possess the skills you lack or are weakest in, right?

I'd hazard that NONE of them have... electrical engineering generally doesn't put you into the high income brackets :-(

...Jim Thompson