Re: subexpressions (OT: math)

2007-06-04 Thread Steve Howell
--- Wildemar Wildenburger <[EMAIL PROTECTED]> wrote: > > > Oh my, remember when we used to discuss murderous > snakes and silly > British comedians on this group? > I hardly do ... > /W Although all of us are mere amateurs in this business of making parameters when it's circles in question I

Re: subexpressions (OT: math)

2007-06-04 Thread Steve Howell
--- Peter Otten <[EMAIL PROTECTED]> wrote: > > I know not much more about Fourier series than that > they do exist, so let me > refer you to > > http://en.wikipedia.org/wiki/Fourier_series > I'd like to try to bring this thread back full circle (or maybe at least 7*pi/4). 1) OP posted an ex

Re: subexpressions (OT: math)

2007-06-04 Thread Wildemar Wildenburger
Peter Otten wrote: > [EMAIL PROTECTED] wrote: > > >> sine is a dimensionless value. >> if we expand sine in taylor series sin(x) = x - (x^3)/6 + (x^5)/120 >> etc. >> you can see that sin can be dimensionless only if x is dimensionless >> too. >> > > With y = x^2 = 1/3 pi^2 - 4(cos x - cos(2

Re: subexpressions (OT: math)

2007-06-04 Thread Peter Otten
Wildemar Wildenburger wrote: > Peter Otten wrote: >> With y = x^2 = 1/3 pi^2 - 4(cos x - cos(2x)/2^2 + cos(3x)/3^2 - ...) >> >> area is dimensionless, too, I suppose. >> > > Ehr, ... maybe this is obvious, but I don't see it: Please explain the > second equality sign. I know not much more abo

Re: subexpressions (OT: math)

2007-06-04 Thread Wildemar Wildenburger
Peter Otten wrote: > With y = x^2 = 1/3 pi^2 - 4(cos x - cos(2x)/2^2 + cos(3x)/3^2 - ...) > > area is dimensionless, too, I suppose. > Ehr, ... maybe this is obvious, but I don't see it: Please explain the second equality sign. /W -- http://mail.python.org/mailman/listinfo/python-list

Re: subexpressions (OT: math)

2007-06-04 Thread Peter Otten
[EMAIL PROTECTED] wrote: > sine is a dimensionless value. > if we expand sine in taylor series sin(x) = x - (x^3)/6 + (x^5)/120 > etc. > you can see that sin can be dimensionless only if x is dimensionless > too. With y = x^2 = 1/3 pi^2 - 4(cos x - cos(2x)/2^2 + cos(3x)/3^2 - ...) area is dimens

Re: subexpressions (OT: math)

2007-06-04 Thread Wildemar Wildenburger
Erik Max Francis wrote: > Wildemar Wildenburger wrote: > > >> So in each term of the sum you have a derivative of f, which in the >> case of the sine function translates to sine and cosine functions at the >> point 0. It's not like you're rid of the function just by doing a >> polynomial exp

Re: subexpressions (OT: math)

2007-06-04 Thread Erik Max Francis
Wildemar Wildenburger wrote: > So in each term of the sum you have a derivative of f, which in the > case of the sine function translates to sine and cosine functions at the > point 0. It's not like you're rid of the function just by doing a > polynomial expansion. The only way to *solve* this

Re: subexpressions (OT: math)

2007-06-04 Thread Wildemar Wildenburger
[EMAIL PROTECTED] wrote: > if you are discordant read more :P : > sine is a dimensionless value. > if we expand sine in taylor series sin(x) = x - (x^3)/6 + (x^5)/120 > etc. > you can see that sin can be dimensionless only if x is dimensionless > too. > > I am a professional physicist and a know ab

Re: subexpressions (OT: math)

2007-06-04 Thread stef
Gary Herron wrote: > Wildemar Wildenburger wrote: > >> Gary Herron wrote: >> >> >>> Of course not! Angles have units, commonly either degrees or radians. >>> >>> However, sines and cosines, being ratios of two lengths, are unit-less. >>> >>> >>> To understand it: sin

Re: subexpressions (OT: math)

2007-06-03 Thread Wildemar Wildenburger
Gary Herron wrote: >> The radian is defined as the ratio of an arc of circumfence of a circle >> to the radius of the circle and is therefore *dimensionless*. End of story. >> http://en.wikipedia.org/wiki/Radian and esp. >> http://en.wikipedia.org/wiki/Radian#Dimensional_analysis >> >> >>

Re: subexpressions (OT: math)

2007-06-03 Thread Steve Howell
--- Alex Martelli <[EMAIL PROTECTED]> wrote: > > I blame the > Babylonians for that > confusion just as much as for the clunky base-60 > that intrudes in our > ordinary time reckoning...! > I apologize for helping to start this whole ridiculous thread, although I hope some people have been ente

Re: subexpressions (OT: math)

2007-06-03 Thread Erik Max Francis
Gary Herron wrote: > No, not end-of-story. Neither of us are being precise enough here. To > quote from your second link: > "Although the radian is a unit of measure, it is a dimensionless > quantity." > > But NOTE: Radians and degrees *are* units of measure., however those > units are dime

Re: subexpressions (OT: math)

2007-06-03 Thread Erik Max Francis
Gary Herron wrote: > Of course not! Angles have units, commonly either degrees or radians. ... > I don't know of any name for the units of "sqrt of angle", but that > doesn't invalidate the claim that the value *is* a dimensioned > quantity. In lieu of a name, we'd have to label such a q

Re: subexpressions (OT: math)

2007-06-03 Thread Alex Martelli
[EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > On 3, 22:07, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > > > > angle is a ratio of two length and > >dimensionless.http://en.wikipedia.org/wiki/Angle#Units_of_measure_for_ang > >les > > > > only dimensionless values can be a argument of a sin

Re: subexpressions (OT: math)

2007-06-03 Thread Lloyd Zusman
"Steven D'Aprano" <[EMAIL PROTECTED]> writes: > On Sun, 03 Jun 2007 11:26:40 -0700, [EMAIL PROTECTED] wrote: > >> if you are discordant read more :P : >> sine is a dimensionless value. >> if we expand sine in taylor series sin(x) = x - (x^3)/6 + (x^5)/120 >> etc. >> you can see that sin can be dim

Re: subexpressions (OT: math)

2007-06-03 Thread Gary Herron
Wildemar Wildenburger wrote: > Gary Herron wrote: > >> Of course not! Angles have units, commonly either degrees or radians. >> >> However, sines and cosines, being ratios of two lengths, are unit-less. >> >> >>> To understand it: sin() can't have dimensioned argument. It is can't >>> t

Re: subexpressions (OT: math)

2007-06-03 Thread Wildemar Wildenburger
Gary Herron wrote: > Of course not! Angles have units, commonly either degrees or radians. > > However, sines and cosines, being ratios of two lengths, are unit-less. > >> To understand it: sin() can't have dimensioned argument. It is can't >> to be - sin(meters) >> >> > No it's sin(rad

Re: subexpressions (OT: math)

2007-06-03 Thread Steven D'Aprano
On Sun, 03 Jun 2007 11:26:40 -0700, [EMAIL PROTECTED] wrote: > if you are discordant read more :P : > sine is a dimensionless value. > if we expand sine in taylor series sin(x) = x - (x^3)/6 + (x^5)/120 > etc. > you can see that sin can be dimensionless only if x is dimensionless > too. > > I am

Re: subexpressions (OT: math)

2007-06-03 Thread Steve Howell
What's the square root of -1 radians? :) Park yourself in front of a world of choices in alternative vehicles. Visit the Yahoo! Auto Green Center. http://autos.yahoo.com/green_center/ -- http://mail.p

Re: subexpressions (OT: math)

2007-06-03 Thread Cameron Laird
In article <[EMAIL PROTECTED]>, Leonhard Vogt <[EMAIL PROTECTED]> wrote: >>> Yes, I understand that, but what is the geometrical >>> meaning of the square root of an arc length? >> >> That's a different question to your original question, which was asking >> about the square root of an angle. >

Re: subexpressions (OT: math)

2007-06-03 Thread [EMAIL PROTECTED]
On 3, 22:07, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > > angle is a ratio of two length and > dimensionless.http://en.wikipedia.org/wiki/Angle#Units_of_measure_for_angles > > only dimensionless values can be a argument of a sine and exponent! > Are you discordant? if you are discordant

Re: subexpressions (OT: math)

2007-06-03 Thread [EMAIL PROTECTED]
On 3, 21:43, Gary Herron <[EMAIL PROTECTED]> wrote: > [EMAIL PROTECTED] wrote: > > > angle is dimensionless unit. > > Of course not! Angles have units, commonly either degrees or radians. > > However, sines and cosines, being ratios of two lengths, are unit-less.> To > understand it: sin() ca

Re: subexpressions (OT: math)

2007-06-03 Thread Gary Herron
[EMAIL PROTECTED] wrote: > On 3, 14:05, Steven D'Aprano <[EMAIL PROTECTED]> > wrote: > >> On Sun, 03 Jun 2007 09:02:11 +0200, Leonhard Vogt wrote: >> bla-bla >> Hmmm... perhaps that's why the author of the "units" program doesn't >> treat angles as dimensionless when

Re: subexpressions (OT: math)

2007-06-03 Thread [EMAIL PROTECTED]
On 3, 14:05, Steven D'Aprano <[EMAIL PROTECTED]> wrote: > On Sun, 03 Jun 2007 09:02:11 +0200, Leonhard Vogt wrote: > >> bla-bla > > Hmmm... perhaps that's why the author of the "units" program doesn't > treat angles as dimensionless when taking square roots. > > Given that, I withdraw my claim

Re: subexpressions (OT: math)

2007-06-03 Thread Steven D'Aprano
On Sun, 03 Jun 2007 09:02:11 +0200, Leonhard Vogt wrote: >> Angles are a ratio of two lengths, and are therefore dimensionless units. >> So the square root of an angle is just another angle, in the same units, >> and it requires no special geometric interpretation: the square root of 25 >> degree

Re: subexpressions (OT: math)

2007-06-03 Thread Leonhard Vogt
>> Yes, I understand that, but what is the geometrical >> meaning of the square root of an arc length? > > That's a different question to your original question, which was asking > about the square root of an angle. > >> And what would the units be? > > Angles are a ratio of two lengths, and

Re: subexpressions (OT: math)

2007-06-02 Thread Hendrik van Rooyen
"Steve Howell" wrote: > > --- Steven D'Aprano > <[EMAIL PROTECTED]> wrote: > > Angles are real numbers (in the maths sense), so > > sqrt(pi/4) radians is > > just as reasonable an angle as pi/4 radians. Both > > are irrational numbers > > (that is, can't be written exactly as the ratio of >

Re: subexpressions (OT: math)

2007-06-02 Thread Steven D'Aprano
On Sat, 02 Jun 2007 08:29:59 -0700, Steve Howell wrote: > > --- Steven D'Aprano > <[EMAIL PROTECTED]> wrote: > >> On Sat, 02 Jun 2007 05:54:51 -0700, Steve Howell >> wrote: >> >> >> >> >>def f(x): y = x*x; return sin(y)+cos(y); >> >> >> > >> > Although I know valid trigonometry is not th

Re: subexpressions (OT: math)

2007-06-02 Thread Steve Howell
--- Steven D'Aprano <[EMAIL PROTECTED]> wrote: > On Sat, 02 Jun 2007 05:54:51 -0700, Steve Howell > wrote: > > >> > >>def f(x): y = x*x; return sin(y)+cos(y); > >> > > > > Although I know valid trigonometry is not the > point of > > this exercise, I'm still trying to figure out why > > an