0128: "dPain over dt"

This forum is for the individual discussion thread that goes with each new comic.

Moderators: Moderators General, Prelates, Magistrates

User avatar
Shoofle
Posts: 409
Joined: Sun Apr 09, 2006 9:28 pm UTC
Location: Location, Location.
Contact:

0128: "dPain over dt"

Postby Shoofle » Fri Jul 14, 2006 4:27 am UTC

Maan, I'm sad because I don't understand it exactly. Let's see . . .
How much she is still in my life minus k1 times pain yields zero when k1=1 and pain=how much she is still in my life. As she leaves my life, this value becomes zero, so long as k1 is positive. If k1 is negative, then this term always increases.
This term multiplied by one over one plus something decaying, once t is greater than k2. After t surpasses k2, the exponential decay increases for increasing values of d. So this whole value (1/(1+e^(-(t-k2)/d))) approaches 1 as t increases, approaching slower if d is smaller and slower if k2 is larger. So this is a damping factor.

So as time increases, the damping factor thing approaches 1. This makes it effectively go away over time. If k1 is positive, then as she leaves my life the value decreases. If k1 is negative, the value increases. So long as k1 is positive, her leaving my life results in a decreased derivative, meaning pain is decreasing faster! Yay! Less pain for the win.


Ugh, thinking that through was painful. Maybe that has to do with it being 12:30 past midnight. That is, it is 30 minutes past midnight. Goodnight.

User avatar
Matt
Posts: 182
Joined: Sat Apr 15, 2006 1:01 am UTC
Location: behind the bottle of Campari

Postby Matt » Sun Jul 16, 2006 7:00 pm UTC

It sure feels like exponential decay.
Hi. I'm from Massachusetts.

Jack Saladin
X is kiss
Posts: 4445
Joined: Thu Jun 15, 2006 8:22 am UTC
Location: Aotearoa

Postby Jack Saladin » Sun Jul 16, 2006 8:41 pm UTC

Yes. Exponential decay, with the, uh, yes.




Yes. >.>

Chubs
Posts: 5
Joined: Sat Jul 08, 2006 9:03 am UTC

Postby Chubs » Wed Jul 19, 2006 10:46 pm UTC

I'm sad because I usually don't get the math ones...

Although on some, like this one, I can appreciate the emotional quality of them... at least.

User avatar
Sitnaltax
Posts: 92
Joined: Tue Jul 04, 2006 10:48 pm UTC
Location: Cleveland

Postby Sitnaltax » Wed Jul 19, 2006 10:59 pm UTC

I guess I'm blessed in that my own pain decay is usually arithmetical and pretty fast, like a week or two for pretty bad stuff.

[Knock wood]

hiddenmaniac
Posts: 42
Joined: Sat Jul 01, 2006 3:25 am UTC
Location: Pittsburgh, PA/Baltimore, MD

Postby hiddenmaniac » Thu Jul 20, 2006 3:24 am UTC

Is her knowledge of calculus a factor you left out?
There are things that don't exist.

Tropylium
Posts: 127
Joined: Tue Jul 25, 2006 9:40 am UTC
Location: Finland

Postby Tropylium » Tue Jul 25, 2006 3:47 pm UTC

0) "How much she's still in my life" = Y. Breikup occurs from t = -x to t = x, x << 1 (with time mezhured in days)

1) Giv'n: dP/dt = (Y(t)-kP)/(1+e^(K-t)/d)

2) For simplicity, let's choose the units so that the presence/pain proportionality constant k = 1. We may do this since there is no other information provided about the relationship of presence and pain.*

2) Common Kno'lij: dP(0)/dt = (Y(0)-P(0))/(1+e^K/d) >> 0 (sharp increase in pain @ breikup)
2a) Y(0) > P(0)
2b) K/d >/> 0

3) CK: P(0) > 0
3a) From this & 2a) follows: Y(0) >> 0

4) CK: dY(0)/dt << 0

5) Is it realistic to assume that d^2P(0)/dt^2 = d^2Y(0)/dt^2 = 0? Ie. that the breik-up will be the steepest increase in pain & drop in presence?

6) CK: Y(1) << 1 (assuming it's a real breikup)
6a) From this & 3a) follows that Y must have the shape of an exponential drop around these parts.

7) CK: P(1) >> 0 (as abov)

…

Anyone wanna continue? I'm starting to get bored here.

Klotz
Posts: 550
Joined: Thu Apr 17, 2008 11:27 pm UTC

Re: "dPain over dt" Discussion

Postby Klotz » Mon Nov 24, 2008 6:13 pm UTC

According to Maple, Pain(t) equals:

[math]Pain \left( t \right) = \left( 1+{e^{-{\frac {t-{\it k2}}{d}}}} \right) ^
{-{\it k1}\,d} \left( {e^{-{\frac {t-{\it k2}}{d}}}} \right) ^{{\it k1
}\,d}{\it \_C1}+ \left( {e^{-{\frac {t-{\it k2}}{d}}}} \right) ^{{\it
k1}\,d}G \left( {e^{ \left( t-{\it k2} \right) {\it k1}}}+{e^{{\frac {
-t+{\it k2}+{\it k1}\,dt-{\it k1}\,d{\it k2}}{d}}}} \right) \left( 1+
{e^{-{\frac {t-{\it k2}}{d}}}} \right) ^{-1}{{\it k1}}^{-1}[/math]

So if k1 is positive it decreases, and if k1 is negative it increases.

skatcat31
Posts: 31
Joined: Tue Nov 25, 2008 12:54 am UTC

Re: "dPain over dt" Discussion

Postby skatcat31 » Tue Nov 25, 2008 2:27 am UTC

Actually it feels more like a graph of both a ln an e value, so while she can be in your life, you will never reach the equalibrium to which there is no pain, so you have two paths that the relationship can take, painful and recurring (e) or painful with an end (ln), so either way you look at it, yes you're boned. But it hurts. But you can have her with you. But it hurts. So you're boned. Mobius strip of the internets strikes again!
I think, without a doubt, I have proven that XKCD is a ghey tranvestite that isalso straight, but a hermaphrodite. Congratulations internets, your mobiusstrip strikes again.

User avatar
Freddino18
[Title Not Found]
Posts: 30
Joined: Thu Oct 27, 2016 9:40 pm UTC
Location: Disappeared after investigating titles

Re: 0128: "dPain over dt"

Postby Freddino18 » Fri Apr 20, 2018 12:36 am UTC

Eight months. Pain has transformed from constant agony to periods of relative normalcy, book-ended by depression and interspersed with occasional bouts of agony, at the same intensity as the beginning.
Image
Blenders!
GENERATION 23: The first time you see this, copy it into your sig on any forum and add 1 to the generation. Social experiment.
Shriekin' Criminal: Wu Tang, Voodoo Foote: pirate, Amos Quirell: wizard, Sun-Ray Fool: blues, Thomaz Hettkamp: Nazi, farty monkey snatcher, phire AvAtAr: 1337 h4x0r


Return to “Individual XKCD Comic Threads”

Who is online

Users browsing this forum: No registered users and 39 guests