Recent content by alecrimi

Hallo everybody. Foreword1: I am an engineer not a physicist Foreword2: I am reading a paper about diffusion MRI who refers to harmonic oscillator hamiltonian. The paper sometimes mention the Fokker Planck equations. Now, I don't want yet understand the relationshipt between...

Thank you. It looks interesting, I will try to digest it

my personal criticism to "Quantum theory and Human conscience" I have to do a couple of premises: 1. There are some previous posts on this arguments, among them I found interesting this one: https://www.physicsforums.com/showthread.php?t=334994 2.This topic requires a deep knowledge in several...

Ok, ok ok ... I have "Geometry and the Immagination" in front of me. (I summarized a bit) Pag. 178: arc length does not make any reference to a particular system of coordinate. For this reason arc length is considered "natural" or intrinsic coordinate of a curve Pag. 205 The Gaussian curvature...

Damn it! Nice question :biggrin: You destroyed our observations, at this point I have no idea. Or we assume my and homeomorphic's observation valid only on 3D representations

I was wondering that a layman explanation can be related to the fact that the principal curvature and their mean are not describing very well intrinsic behaviour of the surface while a product of them can : If the product is positive we are in a parabolic point, if the product is negative we...

Hi all! Let's start from the begin to see where I get lost. Extrinsic curvature defines the way an object relates to the radius of curvature of circles that touch the object (a couple of further nicer definitions come from physics, for the moments I am not mentioning them), and intrinsic...

Hi all! When we talk about the Einstein Field equations. What do we mean with "extremal proper time" or "extremal path"? Why "extremal" ? and why "proper" ? and why do we need to introduce the concept of "geodesic" ? Cheers

yes, it was that. I thought it was something like that. Thanks

why is it defined by "max" ?

Hi I was wondering about the meaning of the infinity norm || x ||_\inf= max\{|x_1|, |x_2|...|x_n| \} if a norm is a function that assigns a strictly positive length or size to all vectors in a vector space, why do we assign the maximum (or sup) as the value of this norm ? It must be a...

Probably my question was not clear. I didn't ask for a definition (everybody can look up wikipedia), I asked when do you need to use them ? some inverse problem... for example ? I am asking when did you meet them, in which phenomena ?

Hi Guys! I have a (stupid) question. In which physical phenomena do you use Volterra equations (or similar equations) ? I mean if we go back to traditional heat,diffusion,wave, transport... and so on we know more or less when to use them. Are integral equation just a dual representation or is...

Hi Sorry for the stupid question, but what is exactly a "stencil" in finite difference methods ? Is the results of the expansion points ? Cheers Alex

Hi Thank you for your reply. Unfortunately... I can't Have you seen my target matrix ? Does it look like anything you can find in a book or was already published ? The expression for a gradient descent works (but it is stuck in a local minimum). I guess it will be solved with a...