April 2nd, 2009

patrickwonders

Ebay Jeebies (take three...)

Brief timeline:

  • Saturday at 8:00pm-ish: Bid on laptop.
  • Sunday at 10:00am-ish: See I won the auction.
  • Sunday just after that: Pay $2050.00 on a Discover card via PayPal
  • Sunday afternoon-ish: Start poking around at seller's identity.
  • Monday all day-ish: Start freaking out that there is no laptop and dreading having to jump through hoops to get PayPal/EBay to refund me.
  • Tuesday at 2:00am-ish: EBay pulls the auction and PayPal launches an investigation.
  • Tuesday at 3:00pm-ish: I email PayPal asking what sort of timeframe I should expect.
  • Wednesday at 9:00am-ish: PayPal tells me they try to resolve everything in less than 30 days, but some things take longer.
  • Wednesday at 4:00pm-ish: PayPal closes investigation and reverses the charges.

So, I'm all back to even. Go EBay and PayPal! Yay!

  • Current Mood
    satisfied satisfied
patrickwonders

Things look nice in lisp...

So, very often for things that I'm toying with, I want to have a polynomial that meets certain criteria. For most applications in the past, I have sat down and figured it all out by hand.

Today, I was having trouble getting the conditions that I wanted specified enough to get the sort of polynomial that I was expecting. After finding the coefficients for several sixth degree polynomials in a row, I figured I should instead be able to do something like this with the proper lisp:

(calculate-polynomial-subject-to (value :at 0 :equals 0) (derivative :at 0 :equals 0) (nth-derivative 2 :at 0 :equals 0) (value :at 1 :equals 1) (derivative :at 1 :equals 0) (nth-derivative 2 :at 1 :equals 0) (value :at 1/2 :equals 3/4))

That's all done now. So, for the record, the above is:

26x3 - 63x4 + 54x5 - 16x6

Which is still not quite what I'm looking for for this application, but it's close.

  • Current Mood
    pleased pleased
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