On 1/6/2012 12:14 PM, Eric Jacobsen wrote: ...> Somebody posted this on FB a while back so I snagged it: > > http://ericjacobsen.org/pics/Math.jpgOuch! Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Internet access during exams
Started by ●January 5, 2012
Reply by ●January 6, 20122012-01-06
Reply by ●January 6, 20122012-01-06
In comp.dsp Clay <clay@claysturner.com> wrote: (snip)> As one who teaches 1st year physics, I've already seen a lot of modes > of cheating. The kids will scan every prior question from the > homework, quizes and tests and what I worked out on the board (they > take pics with their camera phones) and have them in their smart > phones. This is certainly way more advanced for of cheating than > writing stuff on their wrists and feigning a need to go to the > restroom where they have strategically placed papers in the bathroom > trash can. And using cellphone jammers is illegal, so we can't use > that to block access to the internet. Even prisons can't get > permission to jam cellphones.I used to wonder about giving questions in different variables than the formula in the book. If students understand the concept, then letters should't matter. A mass of s=3kg is accelerated by a force of t=9 Newtons, what is the acceleration? Some will look for any forumula with s and t, and plug in the values. -- glen
Reply by ●January 6, 20122012-01-06
On Jan 6, 5:58�pm, glen herrmannsfeldt <g...@ugcs.caltech.edu> wrote:> > I used to wonder about giving questions in different variables > than the formula in the book. If students understand the concept, > then letters shouldn't matter. >Agreed, but on an exam where there is time pressure, it always seemed a bit unfair to use new notation just to test whether they understand the concept. "Let x denote a random variable with density function f_x(X)" just muddies the waters. Dilip Sarwate P.S. Are the roots of the quadratic equation ax^2 + bx + c = 0 given by 2c/[-b +/- sqrt(b^2 - 4ac)] ?
Reply by ●January 6, 20122012-01-06
On 7 Jan, 01:07, dvsarwate <dvsarw...@yahoo.com> wrote:> P.S. Are the roots of the quadratic equation > ax^2 + bx + c = 0 > given by 2c/[-b +/- sqrt(b^2 - 4ac)] ?Saw that claim a couple of years ago. Took me some time to work out the answar, but apparently, that kind of thing[*] is essential in high-accuracy numerical work. Something to do with propagation of errors. Rune [*] Conjugate numbers
Reply by ●January 6, 20122012-01-06
Rune Allnor <allnor@tele.ntnu.no> wrote: (snip, someone wrote)>> P.S. Are the roots of the quadratic equation >> ax^2 + bx + c = 0 >> given by 2c/[-b +/- sqrt(b^2 - 4ac)] ?> Saw that claim a couple of years ago. Took > me some time to work out the answar, but apparently, > that kind of thing[*] is essential in high-accuracy > numerical work. Something to do with propagation > of errors.I once saw a set of values used to stress quadratic solvers written by students for numerical analysis classes. Note that for small ac, sqrt(b^2-4ac) will be close to b, and much precision is lost in the -b+sqrt(b^2-4ac) case. Evaluate the first using -b-sqrt(b^2-4ac), then the second from that, a, and c. I believe that is similar to doing one the usual way, and the other as above. The fastest way to lose precision in floating point is to subtract two nearly identical values. -- glen
Reply by ●January 6, 20122012-01-06
Jerry Avins wrote:> On 1/6/2012 12:14 PM, Eric Jacobsen wrote: > > ... > >> Somebody posted this on FB a while back so I snagged it: >> >> http://ericjacobsen.org/pics/Math.jpg > > Ouch! > > JerryLOL! Prior to my entering freshman class at Cornell, ALL engineering students were required to take a surveying course. The object was to force "pupils" {<> "students"} to use neither slide rules nor log tables for closures (if they did closure error would be too large ;)
Reply by ●January 6, 20122012-01-06
On 1/6/2012 10:32 PM, Richard Owlett wrote:> Jerry Avins wrote: >> On 1/6/2012 12:14 PM, Eric Jacobsen wrote: >> >> ... >> >>> Somebody posted this on FB a while back so I snagged it: >>> >>> http://ericjacobsen.org/pics/Math.jpg >> >> Ouch! >> >> Jerry > > LOL! > Prior to my entering freshman class at Cornell, ALL engineering students > were required to take a surveying course. The object was to force > "pupils" {<> "students"} to use neither slide rules nor log tables for > closures (if they did closure error would be too large ;)You never saw a 10-foot slide rule! :-) (Or a Curta: http://www.vcalc.net/cu.htm) Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●January 7, 20122012-01-07
Jerry Avins wrote:> On 1/6/2012 10:32 PM, Richard Owlett wrote: >> Jerry Avins wrote: >>> On 1/6/2012 12:14 PM, Eric Jacobsen wrote: >>> >>> ... >>> >>>> Somebody posted this on FB a while back so I snagged it: >>>> >>>> http://ericjacobsen.org/pics/Math.jpg >>> >>> Ouch! >>> >>> Jerry >> >> LOL! >> Prior to my entering freshman class at Cornell, ALL engineering students >> were required to take a surveying course. The object was to force >> "pupils" {<> "students"} to use neither slide rules nor log tables for >> closures (if they did closure error would be too large ;) > > You never saw a 10-foot slide rule! :-)Snicker. All the one I saw over lecture hall blackboards were Posts (IIRC). I'd have much more faith in readability/precision of my K&E slapping at my hip ;) [P.S. How many youngsters recognize K&E? ;>!> (Or a Curta: http://www.vcalc.net/cu.htm)Never saw one of those. Suspect would have been as common as an "Analytical Engine" in '61.> > Jerry
Reply by ●January 7, 20122012-01-07
On Fri, 06 Jan 2012 15:14:35 -0500, Jerry Avins <jya@ieee.org> wrote:>On 1/5/2012 5:40 PM, Rune Allnor wrote: >> Just a heads-up / warning for the regulars who answer >> questions and provide other help here: >> >> The Norwegian Ministry of Education is abut to test >> examinations where students have access to internet: >> >> http://www.aftenposten.no/nyheter/iriks/Skeptiske-til--bruke-Internett-p-eksamen-6734506.html >> >> (Haven't found an English version yet; no doubt some will >> pop up as soon the international news stations pick up on >> this lunacy.) >> >> As for now, there is a non-vanishing chance that there >> might pop up questions from students who need answers >> not for homework or projects, but for exams. The idea >> is insane enough to actually spread to other parts of >> the world, so beware; the answers you give here might >> be what get your next colleague his or her diploma... > >I have a small and simple web site on which I have a few recipes and >self-aggrandizing rants. It is now pretty much in disrepair. You can the >public stuff at http://users.rcn.com/jyavins/ , but there's a lot you >can't see. http://users.rcn.com/jyavins/gathering.jpg is one example of >that. It would be easy for me to post pages of facts and formulas if I >had an exam that allowed web access. (So how do you like mt vulture >pictures? One was taken with http://users.rcn.com/jyavins/photoadapter.htm.) > >JerryHey Jerry, Have you ever built an adaptor to turn your lenses around to shoot macro. I was thinking of making one in our shop one day.
Reply by ●January 7, 20122012-01-07
On 1/7/2012 4:45 AM, Mac Decman wrote: ...> Hey Jerry, > Have you ever built an adaptor to turn your lenses around to shoot > macro. I was thinking of making one in our shop one day.No, I haven't. All the automatics and EXIM info is lost that way. I mounted a 2" doublet with about a 6" focal length for use as a close-up attachment to copy 35 mm slides as full-frame digital pictures. It has too much spherical aberration wide open, but it's fine stopped down. I'll send a picture if you like, but it's just a lens in a mount with a 55 mm thread. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
