167 reputation
9
bio website simonwinder.com
location Seattle
age
visits member for 2 years, 9 months
seen Aug 12 at 23:11

I am a software developer and science researcher who is a specialist in computer vision. I worked for Microsoft Research for many years. Now I am an independent consultant and I am starting a robotics company. I work on iOS, OpenGL platforms and also on Windows. I have lots of experience writing fast code using SSE, GPU etc.


Mar
5
comment Finding a simple spline-like interpolating function
OK well you'll be pleased to know that your answer is now incorporated into my iPad app.
Mar
5
comment Finding a simple spline-like interpolating function
Actually my previous statement was false as I realize that introduces a singularity at $\alpha = 0.5$. (Its amazing how little appears on a screen when you have Infs in a vertex shader.) And I guess robotbugs could be both:)
Mar
5
comment Finding a simple spline-like interpolating function
OK thats great because its just $\frac{kx}{x+c}$ which is very few math operations. I can precompute the two constants.
Mar
5
comment Finding a simple spline-like interpolating function
You have a mix of $k$ and $x$ in there. Are they supposed to be the same variable?
Mar
5
comment Finding a simple spline-like interpolating function
Also what did you use to display such a nice graph on here? I was wondering how to get a diagram in my original post. Last time I tried to post something though I did not have enough standing on the forum to post images.
Mar
5
comment Finding a simple spline-like interpolating function
Thanks, thats exactly the form of curve I was looking for. I can certainly live with a square root function. Many thanks!
Mar
5
comment Finding a simple spline-like interpolating function
I'm currently using code: if(d<alpha) d = (1.0-alpha)*d/alpha; else d = (1.0-alpha)+(d-alpha)*alpha/(1.0-alpha); to do a simple 2 piece linear interpolation. The point of my question is finding something smoother and possibly faster to compute.
Mar
5
comment Finding a simple spline-like interpolating function
I tried using a b-spline with three control points at $(0,0)$, $(\alpha,1-\alpha)$, and $(1,1)$ and it looks ok when plotted but the problem is its in a parametric form depending on $t$ and getting a simple $y=f(x,\alpha)$ out of it is painful.
Sep
19
comment Minimize $||Ax-b||$ but for $A$, not $x$
OK thats helpful, thanks.
Sep
18
comment Minimize $||Ax-b||$ but for $A$, not $x$
I corrected the text to clarify the L2 norm.
Sep
18
comment Minimize $||Ax-b||$ but for $A$, not $x$
This is useful but I did intend the L2 norm, which is consistent with the second matrix equation.
Sep
18
comment Minimize $||Ax-b||$ but for $A$, not $x$
Sorry about that it is supposed to be the L2 norm.