Andrew Jaffe

330 reputation

bio	website	andrewjaffe.net/blog
	location	London, United Kingdom
	age	46
visits	member for	5 months
	seen	9 hours ago
stats	profile views	29

Astrophysicist, cosmologist, Mac user, blogger, python fan.

	330 reputation	bio	website	andrewjaffe.net/blog	visits	member for	5 months
19 badges		location	London, United Kingdom		seen	9 hours ago

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May 16	comment	Write a function that returns the logarithmic derivative Note that the expressions like `func[f_]:=f'/f` are not instructions about how to differentiate the particular function `f` that you've defined as "In:"! That is the definition for the pattern `f_` which you just happen to have used the same letter for as your function.
Apr 2	awarded	Enlightened
Apr 2	awarded	Nice Answer
Apr 2	comment	How to change the value of an array that is outside the For loop, from inside the For loop Please put all this in the question! Do you want `H` to be a function of `d`? If so, define it that way.
Apr 2	comment	How to change the value of an array that is outside the For loop, from inside the For loop I think we need more information about what you're actually trying to do. When does `H` change? Inside the `Do`? Should `eigenvect` change when that happens? If so, you need to explicitly call `Eigensystem` each time.
Apr 2	awarded	Commentator
Apr 2	comment	How to change the value of an array that is outside the For loop, from inside the For loop Have you tried that?
Apr 2	comment	How to change the value of an array that is outside the For loop, from inside the For loop Have you tried?
Apr 2	comment	How to change the value of an array that is outside the For loop, from inside the For loop My question/point stands: Do you want `eigenvect` to be different once you've changed `H`? If so, you need to put `Eigensystem[H]` inside the loop (but you don't need to define `H` itself inside the loop). Or do you just want there to be a new `H` once you've finished the loop? In that case, you can just alter `H` itself without calling `Eigensystem`.
Apr 2	comment	How to change the value of an array that is outside the For loop, from inside the For loop It's not clear what you want: do you mean that `eigenvect[]` will change on each iteration? In that case, you need the `Eigensystem[H]` statement inside the loop, too.
Feb 16	awarded	Citizen Patrol
Jan 24	comment	Definite integral takes a very long time Cosmology! (It might actually be useful to allow z>=-1 so it's useful to the future as well as the past...)
Jan 22	comment	Simplification of double symbolic sums containing a DiscreteDelta without explicit summation range @Paco, use backticks for `code`!
Jan 21	revised	How can I efficiently enter multiple instances of data? edited body
Jan 19	answered	How can I efficiently enter multiple instances of data?
Dec 27	revised	Make mathematica treat $e_i^2$ as numeric "threat" -> "treat" and "numerics" -> "numeric"
Dec 27	suggested	suggested edit on Make mathematica treat $e_i^2$ as numeric
Dec 22	revised	What causes this strange convergent sum? added 98 characters in body
Dec 22	comment	What causes this strange convergent sum? Infinite sums are like integrals: even seemingly simple expressions can have complicated answers, and similar expressions can have very different answers.
Dec 22	awarded	Teacher