## Search found 49 matches

Wed Apr 24, 2013 12:33 am UTC
Topic: 1201: "Integration by parts"
Replies: 81
Views: 25617

### Re: 1201: "Integration by parts"

So, I'm a bit confused at all the comments about it not being easy to teach people what, generally, they should use/identify for this technique. I think that a lot of the trouble is that there is usually some fiddle factor that you need to get exactly right. In this example: ∫ x e^(2x) dx You would...
Wed Apr 24, 2013 12:12 am UTC
Forum: Mathematics
Topic: Module intuition
Replies: 7
Views: 2861

### Re: Module intuition

I like the analogy with a group action. If it helps, linear transformations on a vector space form a module, too. (Think about it: linear transformations form a ring, and vectors with addition form an abelian group.) The notion of an "action" (e.g. group action, ring action, module) is pro...
Mon Apr 22, 2013 7:47 am UTC
Forum: Logic Puzzles
Topic: Can you crack my code? Version two
Replies: 10
Views: 7830

### Re: Can you crack my code? Version two

First observation is that there are autocorrelation peaks close to that of English text at offsets 6, 10, 13 and 16. If this is a polyalphabetic system with a cycling key, those are the most likely cycle lengths.
Sun Apr 21, 2013 11:59 pm UTC
Forum: Mathematics
Topic: When should I stop sampling?
Replies: 6
Views: 1880

### Re: When should I stop sampling?

Some might suggest that f is probably well-behaved in the sense that a slight modification of X would lead to a value close to f(X), but I don't want to make that assumption. Why not? This is useful information, and you'd be mad not to use it. Is it because of sampling bias? Then check out the Metr...
Sun Apr 21, 2013 1:12 pm UTC
Topic: 1201: "Integration by parts"
Replies: 81
Views: 25617

### Re: 1201: "Integration by parts"

Demki wrote:Actually, the unique solution to that system of equations is:

Thanks. I've edited it for posterity. Posterity is a nosy bastard, so I'm told.
Sun Apr 21, 2013 3:27 am UTC
Topic: 1201: "Integration by parts"
Replies: 81
Views: 25617

### Re: 1201: "Integration by parts"

OK, I need to rant about this. My guide to integration by parts: It's overly-complicated, and you almost never need it. "Integration by parts" is, as others on this thread have noted, the product rule for differentiation in a different form. However, it's far, far easier to do the product ...
Wed Feb 06, 2008 5:22 am UTC
Topic: 0379: "Forgetting"
Replies: 111
Views: 20328

### Re: "Forgetting" Discussion

Simetrical wrote:How do you know that code isn't in a destructor?

Even in that case, it would be more clearly expressed using a smart pointer, which this clearly isn't.
Tue Feb 05, 2008 10:57 pm UTC
Forum: Mathematics
Replies: 187
Views: 273228