Reputation
981
Top tag
Next privilege 1,000 Rep.
Create new tags
Badges
6 18
Impact
~22k people reached

Apr
10
comment Is there a name for the curve $\sqrt{x} + \sqrt{y} = k$
@RecklessReckoner yeah, the blue part is common to this and "star shaped" thing with four points.
Apr
10
accepted Is there a name for the curve $\sqrt{x} + \sqrt{y} = k$
Apr
10
comment Is there a name for the curve $\sqrt{x} + \sqrt{y} = k$
The a hyperbola $xy=k$ is called a rectangular hyperbola, as, I assume, it's contained by the coordinate axes, rather than the diagonals. I wonder if (un-)rectangular parabola is a suitable name here.
Apr
9
comment Is there a name for the curve $\sqrt{x} + \sqrt{y} = k$
@RecklessReckoner It looks pretty much identical to the parabola $(1+x^2)/2$ rotated about the origin by 45 degrees.
Apr
9
asked Is there a name for the curve $\sqrt{x} + \sqrt{y} = k$
Feb
14
awarded  Popular Question
Oct
6
awarded  Yearling
Oct
6
awarded  Yearling
Jul
2
awarded  Curious
May
15
comment Axis of symmetry of a binary image
I understand that. It seems like a sensible optimisation when there is a single convex shape (and some cases which are not). I was more trying say that even if you skipped the efficiencies it would be faster. I just read what I wrote in the message above, I don't know why I said "compatible to", I definitely meant to say "faster than". That said, the down-/sub- sampling method has the advantage of "softening" the optimisation landscape, and will perform better in some cases - but it really depends on the images, and what kind of result is needed.
May
15
comment Axis of symmetry of a binary image
I would expect, even if you didn't use the binary search, and just brute-forced every possibility, it would still be comparable to a particle based search. i.e. (1000 particles)x(1000 iterations) is probably larger than (180deg at 3deg itervals = 60angles)x(image diagonal in pixels).
May
15
comment Axis of symmetry of a binary image
Indeed, but it's a vanishingly unlikely case. (technically you're not going to do any better than $C_4$ symmetry in an image. - assuming > 1 pixel is different)
May
15
comment Axis of symmetry of a binary image
@String a line of symmetry that passes through the centre of mass would probably be a good starting point for an algorithm.
May
15
revised Axis of symmetry of a binary image
added 95 characters in body
May
15
answered Axis of symmetry of a binary image
May
15
comment Axis of symmetry of a binary image
OK, I'll outline what I mean in an answer.
May
15
comment Axis of symmetry of a binary image
I'd say do it as an optimisation. But you could optimise your optimisation proceedure by doing things like taking a initial approximations using a low resolution image, or by sparsely representing the image in terms of edges, or a randomly sampled subset of your image. It'll still be a bit slow. There's loads of algorithms for these things if you look at the machine vision literature, but if you want something quick and dirty that works, a few optimisations on a brute force search would be the way forward IMO
May
15
comment Find the minimal value of a function
Hint: en.wikipedia.org/wiki/W_function
May
3
comment Matlab iteration
@user142176 The answer is always zero. So function j=iter(p,q,m,e); return 0; end. Also, your code would work if line 3 was j=0, but I think there might be a mistake somewhere in the specification of your problem.
May
3
answered Matlab iteration