>Analysis is better than algebra or topology
/sqt/ Stupid Questions Thread
Angel James
Michael Green
scienceforums.net
>Sun subtends about 0.5 degree on earth surface solid angle Omega becomes = 2pi (1- cos (0.5/2)) = 5,98e-5 steradians
>At bright day light and at 90 degree normal incident, illuminance of sun at earth's surface is around 10.000 lux = lm/m2
>Luminance = illuminance / Omega = 10.000/5,89e-5 =1.67e9 cd/m2
how does this calculation make any sense??
how do you explain the wild discrepancy vs e.g.
>The average luminance B of the sun, observed outside the atmosphere, is a fixed quantity having a value of about 200 000 candles/cm2 . The values of B found in the literature are usually those calculated from the measurements of Bo, the only reference to its direct measurement being that by Teele, who compares his value of 190 000 candles/ cm2 calculated from the normal insolation observed during the 1935 stratosphere flight to "a directly measured value of 200 000 candles/cm2 reported by Worthing"
webcache.googleusercontent.com
Adrian Roberts
fucking retarded sites like wikipedia and others just parrot the same 1.6 Gcd/m^2 without any explanation
Josiah Barnes
Is there a typo here or something? Why is the answer in terms of "N" if x is approaching positive infinity? I know the limit itself equals a negative value, but isn't that irrelevant? The definitions seem to imply that the behavior along the x-axis is what determines the answer.
Top portion of the picture is the definitions, middle is the problem, and bottom is the book's answer. Sorry about the shitty lighting.
Parker Collins
A bit baffled by this one. It's derivates-related.
Justin Taylor
if x is bigger than N, then the difference between f(x) and it's limit at infinity is smaller than epsilon
basic definition of convergence
Zachary Bailey
r'(x) = g'(x)*f'(g(x))
r'(1) = g'(1)*f'(g(1)) = g'(1)*f'(4) = 0 *5/4 = 0
now try it for s
Luke Rogers
>Why is the answer in terms of "N" if x is approaching positive infinity?
N is the number that x has to be greater than to guarantee that f(x) falls within epsilon of -3 man
Think about it, if f(x) has a limit at x going to positive infinity, you can always find some interval for x where f(x) is within an arbitrary fixed value of the limit. This problem is about finding N (and thus a satisfactory interval for x) as a function of the distance, epsilon, from -3, thus showing there's a satisfactory N for *every* distance from -3, proving the limit
Angel Diaz
g(1)=4
f(g(1))=f(4)
f'(4)=?
Angel Gonzalez
It's 5/4 because that's the slope. I'll solve s'(4) then. Thanks!