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For all the old geisers
5

For all the old geisers

For all the old geisers

(OP)
Not too sure where to post this, so I'll do it here

If you remember the days when calculators took a whole room, well this thread's for you.



So what was it like having to do all the calculations by hand? I certainly can't imagine my life without a calculator, probably like most engineers.

Nowadays, people are complaining that we take computers for granted. Some say that many new grads rely to much on them and don't really grasp the theory they are applying.


So my question is : did they have that same argument for calculators back then too?

RE: For all the old geisers

In my second job, I analyzed a truss by hand.  Luckily not a huge truss.  You couldn't use a slide rule, because small differences between large numbers were important.  

I would have killed for the programmable calculator I bought 25 years ago...  but they didn't exist yet.

We did have a calculator... for the whole engineering department.  It was a mechanical Friden thing, larger and heavier than an electric typewriter and with more keys.  It could multiply, which was a big deal for a mechanical calculator, but it did it in a fairly primitive way, so it took a long time.  Division took much longer, made it sound like it was going to spit a gear out, and took minutes.  It was so slow that nobody used it much.  One guy claimed to know how to use it, and would demonstrate it on occasion, but I don't think he really understood it at all.  

Nobody trusted it, either, because it was too easy to not notice a missing keystroke in a long sequence... which was also a problem with the first electronic calcuators.

Actually, that first programmable calculator of mine taught me not to trust them, either.  It used some of the user's registers for its advanced functions, so my first program that used those functions had a bug that drove me crazy for a while.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: For all the old geisers

I was in one of the last few class at the US Navy Nuclear Power School that used slide rules.  A year after the change I stopped back by Vallejo on my way from Long Beach to Bremerton and had a chat instructor that I liked.  I asked him what difference calculators made in the course.  His response was that the material was identical, but the arithmetic on the tests didn't have to resolve as neatly (I don't recall the arithmetic resolving all that neatly in my course work).  "F" still equals "m*a" whether you calculate it on a slide rule, a calculator, or a computer.

The biggest problem I have today is so many people (1) think that a computer model proves anything; and (2) have so little understanding of the arithmetic behind a computer program.  When I was building computer programs in the 80's we had a saying that "if it is on green and white, it must be right" (referring to the preferred printout paper back then).  That sentiment is so pervasive today that when I ask an engineer if he had verified that the assumptions underlying a program were in fact germane to the problem he was solving I get a blank stare.  

The other day I asked an engineer if he had calibrated that a pipeline model matched field data and he was shocked that anyone could question a model.  I showed him how to calibrate the model and found that a whole section had been wired wrong and that his node numbering scheme had fallen into a known bug in that particular software.  He was scandalized to hear that there were known bugs in commercial engineering software.

In the days of slide rules and tabulated data we didn't understand a fraction of what can be included in a design today, but we did have enough sense to question an outrageous answer.

David

RE: For all the old geisers

"...today is so many people (1) think that a computer model proves anything"

Frankly, that's nothing new, hence, my rather flip answer.  30 yrs ago, when our utility bills came on punch cards that weren't to "folded, spindled, or mutilate," there was always the ready answer of, "I sorry, that can't be, it came from the computer, so it can't be wrong."

But, the converse is that if everyone actually understood these basic concepts, we'd all have to be doing something else, because there would be so many more qualified engineers.

I think that you'll find the same basic arguments going back to the days when log tables were introduced, with cognizantis complaining that only logs calculated on a slide rule could be trusted.

TTFN

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RE: For all the old geisers

"I was in one of the last few class at the US Navy Nuclear Power School that used slide rules."

Wow, you remember your class number. I was 8903.  

RE: For all the old geisers

I agree with zdas04.  I transitioned from sliderules to calculators in school.  The professors drilled into us the need for problem setup:  getting the equations down on paper and working through the problem without numbers, only variables.  Then plug & chug at the end.  But to always think about the answer as a validation.

I learned early on the importance of this and failure to trust calculators when my TI-30 failed on me during a physics exam on the topic of optics.  I recall almost losing my self-control and hurling the calculator at the wall.  But the Prof still gave me 85%-95% credit on all the problems.

I taught a "Intro to Engineering" class on occasion and always went through the same challenge with students.  Tried to get them to understand that problem setup is 80% of the solution and I'd give a "B" grade if correct without numerical answers.  But they all relied on calculators, religiously putting 5 or more significant digits on the written answers through all the sequential steps of the problem.  And they thought I was a "hard teacher" because no one finished the tests on time.  Duh.

And, gawdawmighty, you should have heard the wailing and gnashing of teeth when I gave them a simple word problem that had "real life" vagueness and gray areas to read, ponder, and make assumptions upon.

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com

RE: For all the old geisers

I transitioned from sliderules to calculators in 1979 during my research years. Our instructors were very fussy about use of slide rules and log tables. Calculators were a rarity in India and expensive too.

It was the opinion of the faculty that no student should be at a disadvantage as he does not possess a calculator. Hence calculators were banned and use of calculators in exams was considered to be cheating!!

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

RE: For all the old geisers

I'm not old enoguth to really respond but tygerdawgs response got me thinking.

Not sure in the US but in the UK in the 90s all the math & science exams were set up so that the process was more important than the result.

You got marks for the right equations, set up correctly, resolved simplified etc.

In fact I'd guess that less than half of all questions ended up with a numeric answer, it was more normally still in the form of X + 2/3 Y^-1 or the like.

I believe this was deliberately to make calculators of limited use and rely instead on the math.

However, it did little to hone long division or multiplication and I have to admit I'm depressingly poor at these, supposedly part of it is a learning difficulty I have but still, I don't think I'm where I should be.

By the way, I believe the spelling in the OP is wrong and it should be Geezer http://en.wikipedia.org/wiki/Geezer.  I'd have guessed geisers as a miss spelling of geyser and thought it was some joke about older people spouting steam & hot air or something.

KENAT, probably the least qualified checker you'll ever meet...

RE: For all the old geisers

My school was using log tables up to about 1982.  The decision to allow calculators into school caused a lot of discussion (oddly enough, using log tables without knowing how they worked wasn't seen as a problem).

I guess the only times my calculator gave me a real advantage was that it was programmable.  I could program it to solve equations iteratively and to calculate definite integrals - pretty useful for checking your hand-worked answers.

- Steve

RE: For all the old geisers

Luddism, I think, is usually applied to any level of technology, but it's not really about conflict between art and mechanization, it more about the level of control that the technology imposes on you.  We tend to look at technology as a means of controlling our environment, but Luddites point to the overall loss of control, since our control is indirect, and only applied through the technology.  If the technology breaks, we are then helpless, e.g., our current usage of cell phones has reduced the need for pay phones, but if the cell networks went down, we wouldn't even be able to find a payphone.

The OP's concern might be cast in the light of the conflict between the artisans and the factories.  What price did we pay for not knowing how to make our own clothes, and only buy stuff that are cranked out by the millions from factories?  Or, knowing how to forge metals and make our own tools and utensils?

Similarly, I know a programmer who held great disdain for not only VB programmers, but even C programmers, feeling that a "true" programmer programmed in assembly language (he apparently was willing to concede to not programming in machine code) and that anyone who did otherwise was a hack, at best.

TTFN

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RE: For all the old geisers

I weht through College using the sliderule for 99% of my homework, being introduced to computers during the four years too.

Personally, I thought kompeuters were just for analyzing transparent aluminum.

Mike McCann
MMC Engineering

RE: For all the old geisers

At college we were taught to run an order of magnitude approximation first for example, simply by rounding up or down the actual numbers to simple whole numbers, mentally if possible but pencil and paper if not, so as to get an order of magnitude feel for what the right answer should be.
Then when the answer emerged we would know to trust it or not.
Fine for calculations where you use a calculator to step through the calculations.
But if you set up a spreadsheet solution or a use a preset calculation what then? should you know the mechanics of the calculations? shouldn't you know the limitations?
 

JMW
www.ViscoAnalyser.com
 

RE: For all the old geisers

In high school, we had to write a Fortran program and mail it to the state college where they would run it.  I never did get my program to run because of fatal errors, bent cards, out of order etc.  I vowed I would never use a computer again.

In college, the mainframe took the entire basement of the engineering building...  I used to run card punch at the chemistry building, put the box full of cards in a bike and transport them over to the engineering building where they would run the program.  Then cross your fingers and hope it ran.

I used my first PC on the first day I reported to work for my company.  The old Geesers were still talking about the hand cranked Monroe that was in the back room (see the link).  We had just two PC's in the office and the newbie college grad got to figure out how to use the new one.  The surveyor had the other one to run cogo and nobody else could touch it.  No Windows, no mouse.  Eventually taught myself Autocad (version 2.1) using only the arrow keys...  We ran our hydraulic analysis models on a mainframe and it took hours for the program to run.  Eventually I created my own models that took all night to finish, even if they crashed.  Sure makes you double and triple check your data input and assumptions before you hit "run"

http://en.wikipedia.org/wiki/Monroe_calculator
http://www.oldcalculatormuseum.com/calcs.html
http://www.oldcalculatormuseum.com/calcman.html

RE: For all the old geisers

Zogzog,
Class 7203 at Mare Island.

All,
I had a Mech of Matl teacher from Greece.  This blind old jerk was probably the best prepared instructor I ever had.  He had a bunch of rules, but the one that he never varied from is "if the final answer has more significant digits than the given data will support then the question will be graded zero".  It was harsh, and after the first test the class size dropped from 40 to 15, but a whole bunch of years later I still make sure that the digits in the answer are supported by the data (i.e., if I use a pressure of "22" for a calculation then I can't give the answer as "44.123456789".  This was an easy rule to implement with slide rules and log tables, but when your calculator gives you 9 decimal places, why not use them? [anyone who didn't see that statement as sarcasm, needs to think about it].

David

RE: For all the old geisers

"Zogzog,
Class 7203 at Mare Island."

man I didnt know the Ark was nuclear smile. Just raxxing you, I use the same mantra on digits.

My company does testing of high voltage power systems, we have super fancy (And expensive) computerized test equipment that is run off a laptop, you got the idea. Millions of $ in test equipment.

We also have back on a shelf in the shop a "Carbon pile" from around the 1940's, a simpson multimeter, a hand crank TTR, a hand crank megger, and other relics.

When we get a new tech or engineer, he/she, regardless of experience gets to use the old relics for the first few months whenever possible. Then they take the data, manually check it against the specs, manually plot curves if necessary, and after this thread I might just take away thier calculators (The next new guy thanks you all)

Why? They need (IMO) to understand HOW and WHY the equipment works and what is really being done before they get to use the stuff that requires you to hook up the leads and press enter on the laptop.  

RE: For all the old geisers

Zog--

I was right.  I figured your background out along time ago.

I too came up through the "loadbank and phase shifter" school of power system work, and I've worked on carbon pile voltage regulators.

I've watched many a young engineer multiply two numbers with one-decimal precision and proudly display his answer in two-decimal precision like it was significant...

I had to fire a technician once who could not test a relay  without a rack of test sets and an automated test program, and he HONESTLY thought that he could "test any relay we have out there".

old field guy

RE: For all the old geisers

Ah, the world's going to the dogs.
It wasn't like that when I was a lad.
Young people today....  
(Now, where did I leave my teeth?)

JMW
www.ViscoAnalyser.com
 

RE: For all the old geisers

jmw,
I think the real question is "how do you convince kids that the amazing tools available to them are just tools and they are still obligated to understand how the damn things work?"

There are so many cool things available today that weren't even imagined even 10 years ago, but relying on them without understanding the underlying arithmetic is the path towards engineering becoming a craft at the mercy of programmers.

I built a computer system in the early 80's that helped schedule and track preventive maintenance on oil field equipment.  I ended up installing it at 36 facilities--6 successes and 30 miserable failures.  By the last site I had figured out that the key element in success was the age of the maintenance foreman.  If the foreman was over 50, then the installation would be a success.  If he was under 40, I might as well go home.  The guys between 40-50 had a chance, but not much of one.  This seemed counter intuitive until I realized that the "old guys" were looking for a tool to help them do their job better.  The others were looking for a program to do their job for them and weren't willing to put much effort into it.  This discussion is the same thing.  I don't lament the demise of the slide rule as the prime engineering tool--I always hated that thing.  I'm lamenting the application of tools in lieu of understanding.

David

RE: For all the old geisers

Stars for my shipmates

RE: For all the old geisers

The problem with any "tool" or instrument or computer is that it has to be welcomed by the operators, not just understood.

The best and most idiot proof equipment in the world stands no chance of surviving if the operators think it will cost jobs, impact on their perks, or even if they just don't like the bloke from the office (aka the "suit" i.e. anyone in cleaner overalls than they) trying to tell them how they can do a better job with his new fangled kit.

It is surprising how many such innovations get suddenly flooded by the fire hoses, bursting steam lines, hit by fork lift trucks where no fork lift should be, suffer heavy weights falling on them etc. .

I went through an exercise on a lubes facility where the plant manager wanted to improve the de-asphalter control but every time he'd set up the control parameters the operators would come in and set them back to where they wanted them, where they were used to having them.

 

JMW
www.ViscoAnalyser.com
 

RE: For all the old geisers

Sure, it was.  Every generation has a discontuity with the previous one(s).  The REAL difference is that in this particular point in time, there are a mulitude of contemporaneous generational gaps.  

My grandfather was dirt farmer who never even heard of computers.
My father learned to program computers using patch cords.
Somewhere in between was punch cards
I learned simple programming tools like QBasic
My son is like, "What, you have to type in all those commands, where are the drag&drop icons?"

Not much different than when the Jacquard loom automatically cranked out different weaves and patterns, while the older generation then lamented the loss of artistry and the human touch.  The time scale difference is that it took almost 100 years for the next set of major advances to occur, while we're getting major advances in less than 20 years.

Anyone remember the RL02 removable disks?  I used them in 1982.  They were gigantic, about 16-in diameter, and held a piddly 5 MB.  You can't even find a flash drive that holds less than 128 MB in the store now.  You can easily buy a 500 GB HD for lower cost than the RL02 platters alone.  Just this single change has completely revamped the notions of what to store and whether we care.  We've got processors in coffee machines that are more powerful and come more storage than the navigation computer on Apollo 11.  Contrast that with the time lapse between the Jacquard loom and the Hollerith punch card of nearly 100 yrs.

TTFN

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RE: For all the old geisers

Computer programs purchased from the work of computer nerds is not my idea of comprehensive structural analysis. Complacency can be bred into analysis by trusting that all the details have been addressed. Some modern day disasters have been the result of so-called computer routines that may have overlooked some finer details, like connections, wind/snow/rain effects, thermal effects, fatigue, material defects, etc.

In aviation design we had pre-release design reviews staffed by a number of grey beards with a few cycles of experience under their belts. They posed pointed questions that got the design engineers thinking along avenues not considered before.

I remember when early composite fan blades were fabricated and bonded with questionable mid planes. The outer zones were face to face bonded, but the mid plane was the bonded juncture of edges. Typically, in bird strike research, failure was at the midplane, and some engineers even claimed that it was a good thing. I pointed out that all bonded zones should be face to face, not edge to edge. This is the kind of dialogue that comes out of thoughtful considerations of the details, and computer programs are liable to overlook such finer details.

RE: For all the old geisers

What's a removable disk? winky smile

RE: For all the old geisers

Jistre
Its made of vinyl and is covered in a spiral groove, one on each side, made by recording sounds.
By spinning it at about 78rpm and resting a needle in the groove, the vibrations created in the needle are converted to sound in this big trumpet thing like a megaphone.
This is a great device, especially when it is the Ink Spots singing "Whispering Grass", one of my favourites.
 

JMW
www.ViscoAnalyser.com
 

RE: For all the old geisers

Even the Jaz isn't THAT old, and that was 100 MB on a disk that was probably 25 times smaller and 100 times lighter.

As for software, I'm not convinced that argument is valid.  Software is a tool.  The fact that someone uses a staplegun as a hammer shouldn't be blamed on the staple gun.  Things are left off simply because the projects are really too complex for humans to deal with.  I work on a BIG PROGRAM, where there are guys whose sole job is "gap analysis," to determine which ORD requirements weren't flowed or correctly flowed downward, and there are TONS of them.  And this is from an organization CERTIFIED to have the highest possible and best levels of systems engineering processes.

Software does what it's programmed to do, usually...  But, we don't ever seem to get the time tally the checklist of lessons learned so that we can use it for the next project.   

TTFN

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RE: For all the old geisers

In looking through some old technical books, one thing I have noticed is there was more of an attempt to get an analytical solution by whatever means possible.  This might include drastic approximations in the problem set-up.  One drawback on scholastic-type problems was to consider a problem "solved" when no numbers had actually been generated.  For example, you can "solve" a partial differential equation with the solution being a double series with terms of Bessel functions, etc.  Actually turning your "solution" into a stress would then be about on par with running a FEA solution in the first place, which makes it hard to consider that the original problem was actually solved in a meaningful way.

On the significant-digit issue, I remember that being emphasized at various times in school, but those pushing the issue tend to be about as bad as those generating 8-digit decimals.  The problems with that approach are multiple.  The significant digits in your solution are not just dependent on the significant digits in your original numbers, but on the functional relationships and the accuracy of the functional relationships as well.  You can in fact wind up with more significant digits (or fewer) than what you started with.  I vaguely recall one problem from Thermodynamics class where we were using properties read off of a graph, and the uncertainty was amplified such that when we were all done, we couldn't even tell which way the fluid was flowing in the system.

RE: For all the old geisers

I don't see that as a problem generated by the people, per se.  200 years ago, all physics problems that could be solved at all, could be solved analytically.  The tallest building 200 yrs ago, aside from the pyramids, were not more than a few stories tall.  One could contemplate such a building being analyzed with hand solutions.  

When I was in college, MOS transistors could be well represented by a rather simply parabolic equation run on an HP25.  10 yrs later, that equation was no longer applicable, because of short and narrow channel effects.  Body effect became a bigger contributor to the non-ideality of the transistor model.  Likewise, the venerable Ebers-Moll model lasted until the Gummel-Poon model was required to properly model all the parasitic effects that then dominated the bipolar transistor model.

In electro-optics, we used a rather simplistic analytical model 20 yrs ago to determine resolution, detection, recognition, and identication ranges for sensors, all in closed-form algebraic approximations.  The optics performance was treated as diffraction-limited and not a serious impact on performance.  We modeled the diffraction blur as being well less than 1 pixel in size.  Today, the diffraction blur is spread over 4 or 9 pixels.  The optics can no longer be treated as ideal.  Today, we have to use a numerical approximation model that has little analytical traceability to the "real world."  That's also partly be cause we know more about how the eye-brain interface works, so the resolution model of the eye is substantially more complicated than it was 20 yrs ago.

I would contend, therefore, the mere progress of the technology and materials that we use, the change in scale of the physical designs, all collude to require us to use models that can't be solved on a calculator, or even a spreadsheet.  That's the cost of doing business with the latest technology or sensors; we have to use complicated models to accurately reflect the actual performance of systems we analyze.

TTFN

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RE: For all the old geisers

I don't think anyone has said that we should have stopped advancing with 1980's technology (I've never understood why the Amish are happy to use advanced technology from the 19th century but find 20th century stuff evil).  I'm saying that whatever technology we use, we should understand the underlying assumptions and do our best to uncover any hidden limitations.  30 years ago it was so much work to get a beleivable answer to a real-world problem that people tended to make darn sure that they started driving the nail with some sort of hammer instead of the side of a stapler.  Today I see a lot less care in tool selection.

David

RE: For all the old geisers

I used a slide rule in high school; calculators weren't allowed becuase not everyone could afford them. I bought a TI SR-10 in 1973 for $90.

I think young engineers today place too much emphasis on computers. They're seem too eager to create a model for even the simplest things. There's nothing wrong with that but the danger is that they're not thinking through the problem. A computer should be a tool not a crutch. It shouldn't be a substitute for learning how to discern things.

When most things were done by hand, we spent more time thinking about the approach to the analysis or design.  

RE: For all the old geisers

Too tolerant of mistakes?
Bridgebuster's comments suggest that when you do it the hard way you have to be rigorous because you can't afford to make mistakes. With computers it doesn't matter that you get to the end before you find the mistake because it is so easy to correct it and start over. The problem is when this "tolerance" leads to the mistakes not being discovered; perhaps we don't fear mistakes as much as we should.

Consider the spell checker. We type away and then let we correct the spellings that spell checker points out to us. We will miss the mistaken use of their for there because we no longer have the right discipline. Before spell checkers when we wrote directly to the page, you had to get it right first time because too many mistakes meant starting over and even a few mistakes meant getting out the typex.

So, is Word with spell checker better than the old ways? It is certainly more productive but have we learned to use it correctly or lazily?

JMW
www.ViscoAnalyser.com
 

RE: For all the old geisers

With or without a spell checker, Word (or any other WP) is essential for me.  I am not able to put down my thoughts coherently in a linear fashion (i.e., start at the beginning; finish at the end).  I write chunks of prose (manuals, design docs, etc) in a random order and then stitch them together in a WP.  Without a WP I would sit at the beginning with writer's block.

- Steve

RE: For all the old geisers

I really think it boils down to ubiquity and the understanding of the calculation process - having a feel for where you should end up.  The more esoteric the machine or program, the less likely anyone other than the designer will know the limitations of it.  A standard calculator can be given to most folks with an understanding of math and within a few seconds be able to perform many types of calculations with great accuracy and precision.  Hand that person an RPN calculator and they stall for a little while, but can catch up fairly quickly.

With both of these tools, an understanding of the order of operations of math is required to do many multi-step calculations.  With that understanding, they can use parenthesis and the RPN stack to keep things straight.

Now, put them on Excel to do some calcs.  There is a quirk in Excel where the program handles one rule of the order of operations differently than what is generally accepted.  Here's where things get interesting.  Without knowing that quirk, and using the same rules they used with their calculators, they will get different answers with Excel than what their calculators gave them.  If they don't check it with their calculators and they have no feel for what the answer should be, they will blissfully carry on believing that their answer is perfectly correct.

The Garbage In/Garbage Out rule ALWAYS applies, but when the volume of input gets larger (sophisticated programs), or the rules change (unexpected or unknown program assumptions or quirks), it is much easier for garbage to get in.  This is why a much greater understanding of what is going on is required when using more sophisticated tools.


(FYI: for a very lively discussion on the Excel quirk, see these threads:
http://www.eng-tips.com/viewthread.cfm?qid=156861&page=3
http://www.eng-tips.com/viewthread.cfm?qid=157296&page=2)



If you "heard" it on the internet, it's guilty until proven innocent. - DCS

RE: For all the old geisers

Swearingen,
Best example ever.  Thanks.

David

RE: For all the old geisers

SomptingGuy,
25 years ago, you would have put your thoughts on a piece of paper, probably written an outline, then pieced them together for the secretary to type up (hopefully on a Wang).  If your paper was not put together well enough you would have seen first hand "garbage-in garbage-out".
That would have forced a different technique of putting your paper together.

RE: For all the old geisers

Well it was 22 years ago, but yes, she did have a Wang.  There was so must wasted time trying to get bits rearranged when they didn't read quite right.  Plus she wasn't keen on typing little bits here and there - it had to be considered finished.

- Steve

RE: For all the old geisers

"Well it was 22 years ago, but yes, she did have a Wang"

LOL, sounds like a bad New Orleans story.  

RE: For all the old geisers

I think that you're all arguing different things here.  Spell checking isn't quite the same level.  Everyone knows that you cannot get 100% success rate with manual checking, without infinite time.  It's one thing to proof a 5 page memo manually, it's another to proof a 500-page document manually.  

As for calculator usage, I think that you're failing to see that the models in use today can't be checked with a calculator, at least, not in any plausible period of time.  For a simple beam, yes, you can.  For a 100-story building, good luck with that.  

For those in college, are you expecting them to spend 6 yrs to get a BS?  Because that's what it would take for them to learn and understand every bit of any complex modelling approach.  50 yrs ago, you spent 4 years in college and got a BS, with no computers, no calculators, no finite element analysis, etc.  Today, you spend 4 yrs in college and get a BS, but with computers, calculators, finite element analysis, intro to programming, spreadsheets, etc.  Something has to give or people have to spend more time in school.

Much of what I've read here smacks of Luddism.  I can imagine the guild-masters of the mid-19th century demanding that textile workers put in the required years of apprenticeship in the weavers guild so that they can understand the intricacies and complexities of weaving, to prepare them to work in textile factories.  

While I understand the argumens and partially agree, the modern world and education and work is a different place.  My son, freshman in high school, taking honors biology, is being taught stuff we didn't even learn in college.  Likewise, he's already completed a class in Java.  And he's expected to take at least 4 AP classes, while I graduated when 3 AP classes was already beyond the norm.  In order to get all this stuff in, something gets left out.  It used to be that Latin was considered to a mandatory requirement for a high school grad, it got cut out because there were other things that had higher priority.  

What it all boils down to, is that to progress, you stand on the shoulders of giants.  To do that, you have to build on, and not redo, what was done before.  No one expects you to re-derive the Laplace transform.  

Everyone blithely talks about using a calculator to check the math, but no one has argued that you need to understand the intracies of binary and BCD arithmetic to use a calculator.  Why not?  Isn't that just as important as understanding how a slide rule works?  So shouldn't everyone be using slide rules to verify the math?  Is your company going to pay you your salary to verify that Algor's or Mathcads algorithms are all correct and validated?

TTFN

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RE: For all the old geisers

"No one expects you to re-derive the Laplace transform."

Um, I seem to recall doing this at Uni.

In fact the deriviation of various standard equations was the emphasis in a lot of my university classes.  

Maybe it's a UK v US thing.

Then again maybe that wasn't your point IRstuff.

What you say makes a lot of sense, in fact I had further evidence just this morning that I may be a luddite.

At the same time though the point about fundamentally knowing what you're doing, or at least reailizing you don't know what you're doing is a fair one.

KENAT, probably the least qualified checker you'll ever meet...

RE: For all the old geisers

My nuc school days were later than zdas's.  Instructors were relentless about theory.

I think it's a matter of character.  There are those who won't let the convenience of a computer stop them from digging deeper.

Computers have made things easier for those who don't fully grasp theory, but I don't believe it's cut down on the all-too-slim percentage of engineers who aren't content to blindly crunch numbers without a full grasp of "why".

RE: For all the old geisers

I probably am a Luddite, and I damn sure believe that engineers should have an apprenticeship (and I'm really happy that many of my clients are starting to have new graduates work under project-level supervision again).  

I don't know all the intricacies of the computer models that I use, but before I will build a pipeline based on a model run I confirm that if I input known data to that program it gives me the same results as pressure gauges and flow meters give me.  If a model can't match a measured reality then any faith put in an extrapolation is pretty misplaced.

That is my issue, I don't expect every engineer to be able to develop every computer program they run, I just want them to confirm for their self that the model has a reasonable chance of correctly predicting future performance.

David

RE: For all the old geisers

Ignoring Zogzog ...
the secretary had a way of forcing you to bring the document to her complete

RE: For all the old geisers

Computers, calculators and any tools that you can think of is essentially a black box.  If you have the knowledge of what goes on within the black box, by all means, use the tools because it will save you time and money.  If you don't have a full grasp of what's going on in the black box, you are not ready to use the tool.  Especially when the results the black box spits out can potentially kill someone.

Engineers design stuff in one of two ways: by calculations or by testing.  If a product has been tested (numerously) to work, it is a finished product.  If it hasn't been tested, the finished product is based on calculations under numerous assumptions.  You may only find out, after the fact, that some assumptions were incorrect (or made numerical errors), when the product fails.

RE: For all the old geisers

Quote (whyun):

Engineers design stuff in one of two ways: by calculations or by testing.
I do both.  Does that mean I'm not an engineer?

RE: For all the old geisers

"the secretary had a way of forcing you to bring the document to her complete"

This is because prior to the Wang, we used a typewriter - the IBM Selectric being the model I am most familiar with.  Typing a letter or report required the draft to be 100% complete, otherwise the secretary would be required to retype the entire thing (or at least a page or chapter).  Good way to piss off your secretary would be to bring a rough or partial draft for typing and then return it with redlines for retyping.  

http://www.officemuseum.com/typewriters.htm

RE: For all the old geisers

There were a lot of advantages to using a slide rule or hand calculations, advantages I didn't realize until I taught undergraduate engineering.

When folks had to use a slide rule (or even lacking that), they had other processes and rules that aided their work,  specifically ALGEBRA, Scientific Notation,  and ESTIMATION!

"In the old days, us geisers" would do as much of the math (typically meaning algebra) first, then insert the values in scientific notation, and the remaining arithmetic was relatively simple.

The advantage was we knew "about" what the answer was without doing any arithmetic.

Today, by comparison, "kids" will often simply enter a string of numbers into their very capable calculator, then have no choice but to accept the resultant answer, and would not realize something is very wromg with the mass of a 1 cm cube of iron being 9,863,567.263 kg.  

RE: For all the old geisers

I read on the IStructE blog about a suggestion to apply for a UK lottery grant to 'archive' the way engineers work and the tools of the trade. I thought it was a brilliant idea. This would also reflect the thinking and the strategy of engineering design.

I agree with all of the comments about the process of being aware of what you are doing and using the tools to validate your expectations.

When I get a 4-part ring binder calculation for a simple piperack design (a mountain of a molehill!) I always put it aside and ask what's the wind load on the structure, or the stability bracing force? A blank look every time. Sigh....

As swearingen talks about Excel, I have had engineers not know the trig formulae are calculated in radians and they use degrees without recognising the numbers a load of b.......sigh....

Robert Mote
www.motagg.com

RE: For all the old geisers

Tick, same here, kind of.

Back in aerospace/defense in the UK structurally critical elements had to be proven by two separate techniques.

Historically this had been a set of hand calcs (or maybe matlab/mathcad/Excel equivalent) and a test, usually to destruction, of the 'weakest link'.

We were just getting into the realm where a set of hand calcs could be validated using FEA or FEA validated by test.

KENAT, probably the least qualified checker you'll ever meet...

RE: For all the old geisers

mshimko nailed it...

We could run through the basics of the calculations in our heads, on a chalk (remember that?) board or on scratch paper and come up with a general idea of what the answers would be, then we'd go in and refine the calculations and the data, expecting it to be in the general vicinity.  Large departures from the "ballpark" figure meant a closer evaluation of the original ideas.

old field guy

RE: For all the old geisers

Hmm

When I test a car it is essentially a "black box", to which I apply known inputs and measure some outputs.

When I test a 1000 DOF simulation of a car it is essentially a "black box", to which I apply known inputs and measure some outputs.

In both cases I can successfully /test/ the car without understanding what is in the black box. But in both cases, in order to change/develop the car I have to open the black box and rewire it or change some components. But that black box itself contains other black boxes - the sim has the program/OS that it is running in, the real car has a black box called the laws of physics beyond our understanding (eg tires, and I'm not joking, Mr Feynman).  Current world best practice does not rely upon me knowing the gruesome details of the program I use, or knowing any unknowable physics. Certainly, more information about either might help sometimes.

As another example, my background is in testing the dynamics of structures (experimental modal analysis). This is used in the auto industry to correlate with FEA models, for both transfer functions and mode shapes.

At uni I took a lot of structures classes, but skipped FEA as it was very boring and difficult and I was good enough at other topics that I didn't need the marks. Sure, I have picked up some of the theory along the way, but I have never read through the derivation of even the simplest multi dof element formulation.

So, when I build and analyse FEA it is pretty much a black box to me, yet my models run well, correlate well, and make useful predictions.

So I think I can justifiably black box some of my analysis process, although I think we are all happily in agreement that correlation with real world data is the key.

Cheers

Greg Locock

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RE: For all the old geisers

...and while I'm at it I notice the structural engineers refer to 'plug and chug' calculations.

That may be humorous, but it also reveals an acceptance of a degree of black-boxing.

I have an appalling memory, mostly I derive things from first principles, or in the case of structures, E/R=M/I=s/y and a few other goodies.

 

Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: For all the old geisers

... I always have to write down c=f.lambda, although I can happily juggle pV=mRT in my head.

- Steve

RE: For all the old geisers

I graduated with my BSME in 2005, putting me in a generation that has basically always had calculators. However, I still feel I have a good "instinct" for what is reasonable. I think being able to judge "reasonable" comes more from experience than doing arithmatic in your head.

During college, running through enough calculations of a particular type would supply a good instinct for what is reasonable. I also had one teacher that required every final answer to have "reasonable" or "unreasonable" next to it. Then, if you got an answer that you didn't believe, but couldn't find your error, you could get partial credit for recognizing it. I wish more teachers would require this!

I wouldn't argue that advanced tools make it more probable that individuals lose the "instinct" for what is reasonable, but I don't think it's fair to make a generalazation about all us "kids" ;). I personally LOVE hand calculations, so I think I do pretty well at understanding the fundamentals of stress/physics/etc because I am interested. During my BSME, they also drilled us with GIGO (garbage in, garbage out) pretty heavily.

- MechEng2005

RE: For all the old geisers

Reasonable:  I can't think of how many times I've regarded "the answer" and had to as the question:  "Exactly WHEN did the legislature repeal Ohm's Law" or some other inconvenient rule of the universe...

old field guy

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