Mark Eichenlaub

2,191 reputation

1620

bio	website	arcsecond.wordpress.com
	location	Baltimore, MD
	age	28
visits	member for	2 years, 6 months
	seen	May 10 at 0:08
stats	profile views	271

I'm a physics graduate student.

	2,191 reputation	bio	website	arcsecond.wordpress.com	visits	member for	2 years, 6 months
1620 badges		location	Baltimore, MD		seen	May 10 at 0:08

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Mar 20	revised	Logic question: Ant walking a cube deleted 11 characters in body
Mar 20	answered	Logic question: Ant walking a cube
Mar 17	accepted	What am I doing when I separate the variables of a differential equation?
Mar 16	awarded	Nice Question
Mar 16	comment	What am I doing when I separate the variables of a differential equation? Thanks for the link, but the description there is not what you said. Differentials as described in Wikipedia are not infinitesimal changes.
Mar 16	comment	What am I doing when I separate the variables of a differential equation? The $dx$ and $dy$ are coming from a single limit. That's what I've been taught in calculus. This answer is logically equivalent to saying "you can do that because you can do that".
Mar 16	asked	What am I doing when I separate the variables of a differential equation?
Mar 14	comment	What is an intuitive explanation for $\operatorname{div} \operatorname{curl} F = 0$? Why the down votes?
Mar 14	revised	What is an intuitive explanation for $\operatorname{div} \operatorname{curl} F = 0$? added 87 characters in body
Mar 14	revised	What is an intuitive explanation for $\operatorname{div} \operatorname{curl} F = 0$? added 5 characters in body
Mar 14	comment	What is an intuitive explanation for $\operatorname{div} \operatorname{curl} F = 0$? @Billare Thanks. Should say "I'll use Gauss's..."
Mar 14	comment	What is an intuitive explanation for $\operatorname{div} \operatorname{curl} F = 0$? @kake Right. It's not supposed to be a proof so much as a heuristic to suggest the identity might be true.
Mar 14	answered	Non-traditional math concepts for early education
Mar 14	answered	What is an intuitive explanation for $\operatorname{div} \operatorname{curl} F = 0$?
Mar 14	comment	What is an intuitive explanation for $\operatorname{div} \operatorname{curl} F = 0$? I like the analogy to a fluid flow, but for the divergence, were you referring to many needles converging to or diverging from a point rather than one needle? That would make more sense to me since one needle cannot change its shape or grow and shrink. I'm also wary of considering a two-dimensional fluid when the curl is defined in three.
Mar 12	awarded	Nice Question
Mar 11	comment	Find maximum divisors of a number in range @Chan Think of the constraint as a surface in some high-dimensional space. You want to find the spot on the surface where some function is maximized. Then the directional derivative of the function along the surface must be zero in all directions of the surface. The directional derivative is the dot product of the gradient with the tangent to the surface, so the gradient of the function must be normal to the surface. The gradient of the constraint function is also normal to the surface, so these two gradients must differ by only a constant multiplier, called the Lagrange multiplier.
Mar 11	answered	Find maximum divisors of a number in range
Mar 10	awarded	Teacher
Mar 10	answered	Why Circle encloses largest Area?