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Invisible wrote:
> Fredrik Eriksson wrote:
>
>> Basic high-school level math. I am slightly surprised that you did not
>> know it,
>
> What, you mean given that I've never been tought mathematics?
Don't feel bad; my math skills aren't too great either. I just found
this link: http://math.com/
Evidently you can work your way up from basic skills to more advanced
topics. I plan to do so, hopefully achieving the ability to decipher
many of the incomprehensible formulae found at wolfram.com.
Sam
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On 11/16/09 10:12, Darren New wrote:
> Which just goes to show the problem I have with 90% of all matehmatical
> notation. It's so utterly inconsistent that even something like
> (f(f(x))) is ambiguous.
I'm not a mathematician. But I took enough courses that I almost
qualified for an MS in Math (which may well be a BSc in some European
countries, but never mind...).
I can sympathize with them. There simply aren't enough symbols floating
around to accommodate all possible uses. Heck, it's painful enough when
you're typing to be able to type all the standard symbols.
--
Friends help you move. Real friends help you move bodies.
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On 11/16/09 10:21, Darren New wrote:
> Invisible wrote:
>> Just for giggles: how many meanings can you find for "normal"?
>
> Sure. But even differences between things like
>
> sin x^-1 vs sin^-1 x
>
> where the two "^-1" mean entirely different operations. Similarly with
>
> lg^2 X vs lg X^2
Actually, the 2 means the same thing. In both cases, you're squaring.
You're just squaring different quantities.
--
Friends help you move. Real friends help you move bodies.
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On 11/16/09 10:33, Invisible wrote:
>> sin x^-1 vs sin^-1 x
>>
>> where the two "^-1" mean entirely different operations.
>
> The first one, at least, is unambiguous. But the second one? Now do you
> suppose that's the arcsine of x? Or the reciprocol of the sine of x?
I think you'd be hard pressed to find someone who has used it to mean
the reciprocal of the sine. Perhaps that's why they defined the cosecant?
> And then of course, people will write "log x". Wanna take a guess which
> base that is? Now, sometimes it actually doesn't matter which base. And
> if it does, it *probably* means the natural logarithm. Probably...
Go back far enough, and it always meant base e. I wonder when ln(x)
notation cropped up.
If it doesn't matter what base it is, then it'd be "obvious" from the
context.
> Speaking of which, the base of natural logarithms is "e". And sometimes
> "e" means 1 + 1/1 + 1/2 + 1/3 + 1/4... And sometimes "e" is just another
> variable.
You're missing some exclamation symbols.
--
Friends help you move. Real friends help you move bodies.
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On 11/16/09 16:22, andrel wrote:
>> I've also seen pi used more than once as a general variable, rather
>> than a function name or a mathematical constant. This is why you see
>> phrases like "e^(i x) where e is the base of natural logarithms and i
>> is the imaginary unit". Because otherwise it's horrifyingly ambiguous.
>
> I am working in an environment where the imaginary unit is j (because i
> is for current). I have trouble adapting.
Damn them electrical engineers.<G>
When I was an undergrad, I worked at a math tutoring institute. A
number of tutors were EE majors. I once caught one of them trying to
help a student, and he kept writing stuff with j. It was really
confusing her till I pointed out to the tutor that just about everyone
else uses "i". I've met a bunch of guys who didn't know that.
--
Friends help you move. Real friends help you move bodies.
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On 11/16/09 08:59, scott wrote:
> You'd be surprised how many industries require specialist knowledge :-)
> For example, I suspect the structural engineer that designed your
> building did plenty of calculations using calculus to estimate stresses
> based on the loading (simple cases can be looked up in tables, but
> anything unusual needs to be worked out manually). Ditto for an
> electrical engineer who designed the power supply for your computer, the
> DCDC converter in your mobile phone and numerous other circuits -
> without an understanding of calculus you're going to be totally lost.
I somewhat doubt it.
Often, calculus is used in developing the theory. Then the rest is
simply approximations or computers.
When I was taking a statics course, the professor taught us how to
calculate the center of mass by taking the shape, splitting up into
triangles, calculating the center of mass of each (formula for
triangles), and taking the weighted average.
He never once mentioned the generic integral formulation. I asked him
why. He said, "That's good stuff to know if you're going to grad
school/academia, but in the real world, you almost never have the actual
function to integrate."
Which is mostly true. Of course, it's a stretch to say no one in
industry uses calculus, but it's a tiny tiny minority.
> Of course computers can simulate and calculate stuff for you, but you're
> going to look a right idiot if you need to run ten 12 hour simulations
> to decide the correct structure or capacitor size when your colleague
> can work it out exactly in a few minutes with a piece of paper.
If your colleague can work it out quickly on paper, it shouldn't take
long to do it on a computer (Maple, Mathematica, etc). Just because it's
computers doesn't mean it has to be a finite element or Monte Carlo
calculation. Additionally, if it's routine enough, there are handbooks...
--
Friends help you move. Real friends help you move bodies.
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On 11/16/09 16:36, andrel wrote:
>> None of these seem to require knowledge of calculus. In fact, jobs
>> that *do* require such knowledge are seemingly so absurdly rare that I
>> almost find it difficult to believe they exist.
>
> So I don't exist? Nor do many of my collegues?
> I think I disagree.
I think your job _is_ fairly rare. Even among people in technical fields.
Does it require a PhD?
There you go.
Perhaps he exaggerated a bit, but to be honest, it *is* fairly hard to
get a job outside of academia that requires calculus knowledge, and
doesn't require a graduate degree (at least in the US).
It's kind of like people who know advanced CS, and are depressed to
find almost all jobs for programmers are for code monkeys. Although I'm
sure there are some good jobs that don't require a graduate degree in CS...
--
Friends help you move. Real friends help you move bodies.
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On 11/16/09 10:09, Darren New wrote:
> Invisible wrote:
>> What the hell is the derivative of f(f(x))?
>
> LMATFY
You really shouldn't start any acronym with LMA... It was quite
anticlimactic.
--
Friends help you move. Real friends help you move bodies.
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Neeum Zawan <m.n### [at] ieee org> wrote:
> On 11/16/09 10:21, Darren New wrote:
> > Invisible wrote:
> >> Just for giggles: how many meanings can you find for "normal"?
> >
> > Sure. But even differences between things like
> >
> > sin x^-1 vs sin^-1 x
> >
> > where the two "^-1" mean entirely different operations. [/snip]
It's actually the same operation, you are just inverting different objects with
respect to different operations. In the first case you are inverting a number
(x) with respect to multiplication, in the second case you are inverting a
function (sin) with respect to composition.
It's similar to how sin and sin(x) are not the same thing. sin is a function and
sin(x) is the value of said function at the number x.
Mindblow anyone? :)
Regards Roman
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>> I've also seen pi used more than once as a general variable, rather
>> than a function name or a mathematical constant. This is why you see
>> phrases like "e^(i x) where e is the base of natural logarithms and i
>> is the imaginary unit". Because otherwise it's horrifyingly ambiguous.
>
> I am working in an environment where the imaginary unit is j (because i
> is for current). I have trouble adapting.
Hahaha.
Arbitrary conventions FTW!
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>> Speaking of which, the base of natural logarithms is "e". And sometimes
>> "e" means 1 + 1/1 + 1/2 + 1/3 + 1/4... And sometimes "e" is just another
>> variable.
>
> You're missing some exclamation symbols.
Oh, so it's actually 1/n! then? I didn't actually know that...
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> * equivalence, equality, definition, EXNOR, assignment and perhaps one
> or more that don't have names.
I'm failing to see how equivalence and definition are different. (I know
some people use the triple-line symbol for this though.)
The main confusion is between assignment and equality, generally. Or, in
mathematics, between a test for equality and a statement of equality.
> ** See also the concept of '=' in OO languages. Are two objects the same
> if all fields are the same?
You would first have to define the concept of fields being "the same". ;-)
Fortunately, in a pure functional language, the question becomes a lot
simpler.
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stbenge wrote:
> hopefully achieving the ability to decipher
> many of the incomprehensible formulae found at wolfram.com.
Yeah, good luck with that. ;-)
Wolfram plays with some pretty advanced stuff. Between the Euler gamma
function, the Riemann zeta function, spherical harmonics, elliptic
integrals, Pochammer symbols, Godel numbers, hypergeometric functions,
the Airy functions and so forth... it could take a lifetime to learn all
this stuff.
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>> None of these seem to require knowledge of calculus. In fact, jobs
>> that *do* require such knowledge are seemingly so absurdly rare that I
>> almost find it difficult to believe they exist.
>
> So I don't exist? Nor do many of my collegues?
> I think I disagree.
Logically, I know such people must exist somewhere. They're just so rare
it sometimes seems difficult to really *believe* they exist.
>> I mean, doing a job that requires mathematics is like being an olympic
>> athlete. Hypothetically, anybody can become an olympian. But seriously
>> guys, how many olympians have you personally met?
>
> none, but I can name a few who know a lot of them.
>
> You could also have asked for e.g. opera singers. Most people also know
> none of those. OTOH I think I have met more than 10.
>
> So it is all just a matter of who you know and who they know.
Professional singers, actors, athletes, musicians, dancers... I don't
know any of these people. Admittedly I don't know a huge number of
people, but my point is just that people who do specialised stuff like
that are very rare.
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Neeum Zawan wrote:
> On 11/16/09 10:33, Invisible wrote:
>>> sin x^-1 vs sin^-1 x
>>>
>>> where the two "^-1" mean entirely different operations.
>>
>> The first one, at least, is unambiguous. But the second one? Now do you
>> suppose that's the arcsine of x? Or the reciprocol of the sine of x?
>
> I think you'd be hard pressed to find someone who has used it to
> mean the reciprocal of the sine. Perhaps that's why they defined the
> cosecant?
>
Neither is unambiguous, really. The first one I might read as either
(sin x)^-1 or sin(x^-1). The second I have seen used to represent both
cosecant and arcsin. All depending on which professor was scribbling the
function.
>> And then of course, people will write "log x". Wanna take a guess which
>> base that is? Now, sometimes it actually doesn't matter which base. And
>> if it does, it *probably* means the natural logarithm. Probably...
>
> Go back far enough, and it always meant base e. I wonder when ln(x)
> notation cropped up.
>
> If it doesn't matter what base it is, then it'd be "obvious" from
> the context.
>
My high school and college professors learned from a different book.
ln(x) was always natural log, while log(x) was either base 10 for the
normal math courses or base 2 for the computer courses. Most of the
time, people were expected to place a subscript noting the base.
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> As far as I can tell, the majority of people in the world have jobs
> like... Telemarketing. Driving trucks. Working in an office doing filing.
> Fitting central heating systems. Hotel receptionists.
Yes, the majority of people do a wide variety of jobs :-)
> None of these seem to require knowledge of calculus. In fact, jobs that
> *do* require such knowledge are seemingly so absurdly rare that I almost
> find it difficult to believe they exist.
I'd say most Chartered Engineers would have used calculus in their job at
some point or another, there's 180000 of them in the UK. Call that absurdly
rare if you want.
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>> As far as I can tell, the majority of people in the world have jobs
>> like... Telemarketing. Driving trucks. Working in an office doing
>> filing. Fitting central heating systems. Hotel receptionists.
>
> Yes, the majority of people do a wide variety of jobs :-)
More precisely: The majority of people are in service jobs. (At least,
in the UK.) Used to be manufacturing, now it's service.
As far as I can tell, higher math is more relevant to design and
engineering, which is quite rare.
>> None of these seem to require knowledge of calculus. In fact, jobs
>> that *do* require such knowledge are seemingly so absurdly rare that I
>> almost find it difficult to believe they exist.
>
> I'd say most Chartered Engineers would have used calculus in their job
> at some point or another, there's 180000 of them in the UK. Call that
> absurdly rare if you want.
What's a chartered engineer? And how do you know how many there are?
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> When I was taking a statics course, the professor taught us how to
> calculate the center of mass by taking the shape, splitting up into
> triangles, calculating the center of mass of each (formula for triangles),
> and taking the weighted average.
>
> He never once mentioned the generic integral formulation. I asked him why.
> He said, "That's good stuff to know if you're going to grad
> school/academia, but in the real world, you almost never have the actual
> function to integrate."
>
> Which is mostly true.
I guess it depends exactly what you're doing in the real world, but in the
situations where I've used calculus I've known exactly the function to
integrate (eg force applied at an exact point during a test). If I didn't
know the exact function I wouldn't be able to ask a finite element solver to
do it either!
> If your colleague can work it out quickly on paper, it shouldn't take long
> to do it on a computer (Maple, Mathematica, etc).
Sure, but the point is you need to have a good knowledge of calculus to even
ask Maple of Mathematica to do such things. If you have never been taught
calculus at university then good luck trying to solve the problem with a
computer math tool like Mathematica!
> Just because it's computers doesn't mean it has to be a finite element or
> Monte Carlo calculation.
It does for people who don't know calculus.
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On 11/17/09 03:17, Invisible wrote:
>>> Speaking of which, the base of natural logarithms is "e". And sometimes
>>> "e" means 1 + 1/1 + 1/2 + 1/3 + 1/4... And sometimes "e" is just another
>>> variable.
>>
>> You're missing some exclamation symbols.
>
> Oh, so it's actually 1/n! then? I didn't actually know that...
Yep. What you listed diverges to infinity.
--
Be independent! No, not that way! This way!
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On 11/17/09 08:09, scott wrote:
>> If your colleague can work it out quickly on paper, it shouldn't take
>> long to do it on a computer (Maple, Mathematica, etc).
>
> Sure, but the point is you need to have a good knowledge of calculus to
> even ask Maple of Mathematica to do such things. If you have never been
> taught calculus at university then good luck trying to solve the problem
> with a computer math tool like Mathematica!
Sure, but not that much. I know people who've correctly used computers
to do this while they thought that the integral of a product is the
product of the integrals.
--
Be independent! No, not that way! This way!
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>>>> Speaking of which, the base of natural logarithms is "e". And sometimes
>>>> "e" means 1 + 1/1 + 1/2 + 1/3 + 1/4... And sometimes "e" is just
>>>> another variable.
>>>
>>> You're missing some exclamation symbols.
>>
>> Oh, so it's actually 1/n! then? I didn't actually know that...
>
> Yep. What you listed diverges to infinity.
Hmm. Interesting...
Nice to know I fail basic math, eh? Fortunately, lives do not depend on
it. o_O
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> What's a chartered engineer?
Someone who has spent at least 5 years (usually) in an Engineering job, then
got professional membership with an accredited Engineering organisation.
This usually involves writing a report of what Engineering stuff you've done
in your job and passing an interview. Needless to say, Chartered Engineers
are "proper" Engineers, which is why it is a requirement for many jobs at
senior level, especially in safety critical industries like structural and
aeronautical engineering.
> And how do you know how many there are?
http://en.wikipedia.org/wiki/Chartered_Engineer_%28UK%29
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> Sure, but not that much. I know people who've correctly used computers
> to do this while they thought that the integral of a product is the
> product of the integrals.
Let's hope they're not involved in any safety critical projects then :-)
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Invisible wrote:
> I'm failing to see how equivalence and definition are different.
I'm thinking you have the choice of
x == y
x.isEqual(y)
and
(let x := y in (....)) or {const int x = y}
for equality, equivalence, and definition?
Two abstract structures can be equivalent without being equal. Definition is
an arbitrary assignment of a meaning to a formal name.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New wrote:
> Invisible wrote:
>> I'm failing to see how equivalence and definition are different.
> Two abstract structures can be equivalent without being equal.
Oh, I see.
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On 11/17/09 09:50, scott wrote:
>> Sure, but not that much. I know people who've correctly used computers
>> to do this while they thought that the integral of a product is the
>> product of the integrals.
>
> Let's hope they're not involved in any safety critical projects then :-)
You're in the UK, and that may make the difference. I know that in the
distant past, it was significantly challenging to get admission into a
UK university to do engineering. So it would make sense if over there
it's common for engineers to use calculus. For lesser jobs, you have
people who don't have engineering degrees (technical degrees, associates
degrees, etc).
In the US, people with engineering degrees do both those kinds of jobs
- it spans a wider spectrum. Which is why perhaps most jobs here that
require an engineering degree often don't require calculus. Hence the
analogy with programming and computer science.
Sadly, here in the US it's common to have people graduating with a
bachelor's degree in engineering who've forgotten most of calculus (they
weren't bad at it - that person I mentioned never got less than an A in
any math course). So perhaps the industry in the US has somewhat shifted
not to expect them to know it, and thus most don't hire them for jobs
that require it.
Of course, some jobs simply *require* it (e.g. electromagnetics related
jobs). And they do hire people with BSc degrees. But of course, they
make sure they know calculus in the interview.
My experience is limited to electrical engineering. It may be different
in other engineerings.
--
Be independent! No, not that way! This way!
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scott wrote:
>> As far as I can tell, the majority of people in the world have jobs
>> like... Telemarketing. Driving trucks. Working in an office doing filing.
>> Fitting central heating systems. Hotel receptionists.
>
> Yes, the majority of people do a wide variety of jobs :-)
And most natural numbers are very very big.
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On 17-11-2009 10:20, Invisible wrote:
>> * equivalence, equality, definition, EXNOR, assignment and perhaps one
>> or more that don't have names.
>
> I'm failing to see how equivalence and definition are different.
If you say that f(x)=x^2+4x+1 then that is an equivalence, because that
will allow you to conclude say that x^2+3x+3=f(x)-x+2. If, however, this
is the first time you mention f(x) it is probably meant as it's
definition. Difference is subtle and has mathematically no significance,
but it feels different. Just as x=5 seen as a statement that the
solution to the problem is when you take x to be 5, feels different from
viewing = as a boolean function of two variables, x and 5.
>(I know some people use the triple-line symbol for this though.)
>
> The main confusion is between assignment and equality, generally.
That is why most languages have separate symbols for both meanings (and
why I am advocating imperative languages without assignment).
> Or, in mathematics, between a test for equality and a statement of equality.
Can you give an example of that?
>> ** See also the concept of '=' in OO languages. Are two objects the
>> same if all fields are the same?
>
> You would first have to define the concept of fields being "the same". ;-)
spot on
> Fortunately, in a pure functional language, the question becomes a lot
> simpler.
Not so sure about that. Anyway even if that would be the case it doesn't
solve the 'problem' that in real life you have multiple views to look at
an equation.
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> Sadly, here in the US it's common to have people graduating with a
> bachelor's degree in engineering who've forgotten most of calculus
Yeh see I don't think that could happen here. My course was 4 years (as are
most Engineering degrees in the UK now), in the 1st year they *really*
quickly skipped over all A level maths (which was the foundations of
calculus) and then jumped on to fourier transforms (and friends), vector
calculus and stuff. The reason for this was clear, all the other lecturers
were obviously waiting for the maths course to be done so they could start
using the "real" maths in their courses.
> any math course). So perhaps the industry in the US has somewhat shifted
> not to expect them to know it, and thus most don't hire them for jobs that
> require it.
I don't think many jobs here explicitly require it, but it is kind of
expected that if you have an Engineering degree you will at least know how
to perform basic calculus by hand, and of course know the concepts.
I guess it's similar to whether you know how to write Excel macros or not -
hardly any job is going to ask for it, yet if you know how to do it it's
going to make life quite a lot easier in many situations that arise (and
make your boss think you are clever!).
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Nicolas Alvarez wrote:
> And most natural numbers are very very big.
Unnatural numbers FTW!
7
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>> (I know some people use the triple-line symbol for this though.)
>>
>> The main confusion is between assignment and equality, generally.
>
> That is why most languages have separate symbols for both meanings (and
> why I am advocating imperative languages without assignment).
Heh. How many C programs fail because people use "=" instead of "=="?
(Most strongly-typed languages manage to catch this mistake. C is
deliberately designed to make this mistake a valid program construct.
Friggin' weirdos...)
>> Or, in mathematics, between a test for equality and a statement of
>> equality.
>
> Can you give an example of that?
If I say "x = sqrt(y/z)", do I mean that x *is* equal to this RHS? Or is
it an equation that must be solved by *making* x equal to the RHS?
Similarly, this fragment can appear inside a statement, such as "f(x) =
3 if x = sqrt(y/z), otherwise 9". In that case, the "x = sqrt(y/z)" part
is clearly a conditional test.
So "x = sqrt(y/z)" can mean:
- x *is* equal to this.
- you must *make* x equal to this.
- please *test* whether x is equal to this.
As you point out, there's also the distinction between "x just happens
to equal this thing" and "x is defined as being this thing".
>>> ** See also the concept of '=' in OO languages. Are two objects the
>>> same if all fields are the same?
>>
>> You would first have to define the concept of fields being "the same".
>> ;-)
>
> spot on
Hence deep-equal and shallow equal, value-equal and reference-equal.
>> Fortunately, in a pure functional language, the question becomes a lot
>> simpler.
>
> Not so sure about that.
If data cannot be altered, it is not possible to distinguish between two
objects which are reference-equal and two objects which are merely
value-equal.
The question of deep/shallow still arises, and you still have to decide
whether you mean "identical" or just "equivilent" (which will generally
depend on what the data *means*). But you don't have to worry about
reference-equal any more, which is a significant simplification.
(Until you start dealing with mutable data. In that case, since equality
is a pure operation, it is natural that you should consider only
reference-equality. Indeed, Haskell's type system *demands* this.)
> Anyway even if that would be the case it doesn't
> solve the 'problem' that in real life you have multiple views to look at
> an equation.
Indeed.
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On 11/18/09 02:10, scott wrote:
>> Sadly, here in the US it's common to have people graduating with a
>> bachelor's degree in engineering who've forgotten most of calculus
>
> Yeh see I don't think that could happen here. My course was 4 years (as
> are most Engineering degrees in the UK now), in the 1st year they
> *really* quickly skipped over all A level maths (which was the
> foundations of calculus) and then jumped on to fourier transforms (and
> friends), vector calculus and stuff. The reason for this was clear, all
Over here, while many do it in high school, almost all engineering
programs have up to 3 semesters of calculus in undergrad (sometimes one
can "test out" of those if their high school education was good enough).
I've been to both a low ranked university (undergrad) and a top
engineering university (grad). In both places, I complained that the
upper level (undergrad) engineering courses rarely required the students
to be able to solve differential equations or perform integrals. The
exception was electromagnetics, where you just can't do without them.
And some courses would require it for calculating Fourier
coefficients/transforms, but those weren't challenging integrals. In all
other courses where, say, a diff eq would crop up, the professor would
almost always say - "Let's not get distracted by the math - this is an
engineering course. Here's the solution: You can verify it by plugging
it back into the diff eq."
It probably wasn't always this way.
--
I didn't know my husband drank until one day he came home sober.
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"Fredrik Eriksson" <fe79}--at--{yahoo}--dot--{com> wrote:
> On Mon, 16 Nov 2009 13:39:50 +0100, Invisible <voi### [at] devnull> wrote:
> > Suppose that the first derivative of f(x) is g(x).
> >
> > What the hell is the derivative of f(f(x))?
>
> http://www.google.com/search?q=What+is+the+derivative+of+a+composite+function%3F
>
> http://en.wikipedia.org/wiki/Chain_rule
>
> Basic high-school level math. I am slightly surprised that you did not
> know it, though I am not in the least surprised that you did not bother to
> google for it.
>
Already knowing the answer could mean already being familiar with the terms
"composite function" and "chain rule". It wasn't necessarily a stupid question.
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On 18-11-2009 11:35, Invisible wrote:
>>> (I know some people use the triple-line symbol for this though.)
>>>
>>> The main confusion is between assignment and equality, generally.
>>
>> That is why most languages have separate symbols for both meanings
>> (and why I am advocating imperative languages without assignment).
>
> Heh. How many C programs fail because people use "=" instead of "=="?
>
> (Most strongly-typed languages manage to catch this mistake. C is
> deliberately designed to make this mistake a valid program construct.
> Friggin' weirdos...)
No, if they did it differently it would break other functionality.
>>> Or, in mathematics, between a test for equality and a statement of
>>> equality.
>>
>> Can you give an example of that?
>
> If I say "x = sqrt(y/z)", do I mean that x *is* equal to this RHS? Or is
> it an equation that must be solved by *making* x equal to the RHS?
Or is it the definition of z because x and y are known.
And there is still the other interpretation of being false everywhere in
3D space except on some curves planes.
> Similarly, this fragment can appear inside a statement, such as "f(x) =
> 3 if x = sqrt(y/z), otherwise 9". In that case, the "x = sqrt(y/z)" part
> is clearly a conditional test.
I don't remember 'if' being part of my maths course. Yet yhere must be
specialized subfields where it is defined.
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>> Similarly, this fragment can appear inside a statement, such as "f(x)
>> = 3 if x = sqrt(y/z), otherwise 9". In that case, the "x = sqrt(y/z)"
>> part is clearly a conditional test.
>
> I don't remember 'if' being part of my maths course. Yet yhere must be
> specialized subfields where it is defined.
How about
sinc(x) = if x = 0 then 1 else sin(x) / x
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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On 18-11-2009 22:52, Orchid XP v8 wrote:
>>> Similarly, this fragment can appear inside a statement, such as "f(x)
>>> = 3 if x = sqrt(y/z), otherwise 9". In that case, the "x = sqrt(y/z)"
>>> part is clearly a conditional test.
>>
>> I don't remember 'if' being part of my maths course. Yet yhere must be
>> specialized subfields where it is defined.
>
> How about
>
> sinc(x) = if x = 0 then 1 else sin(x) / x
>
nope, never seen that
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andrel wrote:
> On 18-11-2009 22:52, Orchid XP v8 wrote:
>>>> Similarly, this fragment can appear inside a statement, such as
>>>> "f(x) = 3 if x = sqrt(y/z), otherwise 9". In that case, the "x =
>>>> sqrt(y/z)" part is clearly a conditional test.
>>>
>>> I don't remember 'if' being part of my maths course. Yet yhere must
>>> be specialized subfields where it is defined.
>>
>> How about
>>
>> sinc(x) = if x = 0 then 1 else sin(x) / x
>>
> nope, never seen that
I've seen it as
sinc(x) = 1 if x = 0
sinc(x) = sin(x)/x if x /= 0
I've never seen it written with an else.
--
Darren New, San Diego CA, USA (PST)
Is God willing to prevent phrogams, but not able?
Then he is not omnipotent.
Is he able, but not willing, to prevent phrogams?
Then he is malevolent.
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> And some courses would require it for calculating Fourier
> coefficients/transforms, but those weren't challenging integrals. In all
> other courses where, say, a diff eq would crop up, the professor would
> almost always say - "Let's not get distracted by the math - this is an
> engineering course. Here's the solution: You can verify it by plugging it
> back into the diff eq."
Yeh, I guess it depends whether you want to be someone who just uses
pre-existing results to "Engineer" run-of-the-mill stuff, or you actually
want to work with cutting-edge concepts and develop new stuff. Me, I prefer
the latter, but maybe that was just because of the way my degree was
oriented.
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>>> How about
>>>
>>> sinc(x) = if x = 0 then 1 else sin(x) / x
>>>
>> nope, never seen that
>
> I've seen it as
> sinc(x) = 1 if x = 0
> sinc(x) = sin(x)/x if x /= 0
In our math classes we always wrote it just like that, but usually only the
"sinc(x)" once and a curly bracket around the two options IIRC.
> I've never seen it written with an else.
Me neither, that sounds more like a programming language than math notation.
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>>>> How about
>>>>
>>>> sinc(x) = if x = 0 then 1 else sin(x) / x
>>>>
>>> nope, never seen that
>>
>> I've seen it as
>> sinc(x) = 1 if x = 0
>> sinc(x) = sin(x)/x if x /= 0
>
> In our math classes we always wrote it just like that, but usually only
> the "sinc(x)" once and a curly bracket around the two options IIRC.
Indeed. But you can't really do that with ASCII, so I wrote the nearest
equivilent.
>> I've never seen it written with an else.
>
> Me neither, that sounds more like a programming language than math
> notation.
Well, technically the above *is* a valid Haskell function declaration...
[Or rather, it becomes so if you change "if x = " to "if x == 0" - which
probably proves Andrel's original point.]
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On 11/19/09 02:15, scott wrote:
> pre-existing results to "Engineer" run-of-the-mill stuff, or you
> actually want to work with cutting-edge concepts and develop new stuff.
> Me, I prefer the latter, but maybe that was just because of the way my
> degree was oriented.
Except that in engineering over here, that often requires a Masters
degree. People with bachelor's in engineering rarely do development.
They may play some role in the process, but it's rare that they'll
actually be key people in the design process.
--
I didn't know my husband drank until one day he came home sober.
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>> pre-existing results to "Engineer" run-of-the-mill stuff, or you
>> actually want to work with cutting-edge concepts and develop new stuff.
>> Me, I prefer the latter, but maybe that was just because of the way my
>> degree was oriented.
>
> Except that in engineering over here, that often requires a Masters
> degree. People with bachelor's in engineering rarely do development. They
> may play some role in the process, but it's rare that they'll actually be
> key people in the design process.
Bachelor Engineering degrees don't really exist in the UK anymore, nearly
all engineering degrees are Masters now. Of course there are non-degree
Engineering qualifications you can do which are probably more suited to the
non-development stuff and not as theoretically based.
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On 11/20/09 03:13, scott wrote:
> Bachelor Engineering degrees don't really exist in the UK anymore,
> nearly all engineering degrees are Masters now. Of course there are
> non-degree Engineering qualifications you can do which are probably more
> suited to the non-development stuff and not as theoretically based.
Which was my point all along. In the UK, I'm guessing those technical
degrees (that are "less" than a Bachelor's) is not a rare thing. Over
here, it's quite uncommon. The Bachelor's degree over here fills that
role (and more advanced ones - it's quite broad).
--
Two robins were sitting in a tree. `I'm really hungry`, said the first
one. `Me, too` said the second. `Let's fly down and find some lunch.`
They flew to the ground and found a nice plot of plowed ground full of
worms. They ate and ate and ate and ate `til they could eat no more.
`I'm so full I don't think I can fly back up to the tree`, said the
first one. `Me either. Let's just lay here and bask in the warm sun`,
said the second. `O.K.` said the first. They plopped down, basking in
the sun. No sooner than they had fallen asleep, a big fat tom cat snuck
up and gobbled them up. As he sat washing his face after his meal, he
thought, `I just love baskin` robins.`
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