Rank: 5 based on 4249 downloads (last 30 days) and 52 files submitted
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John D'Errico

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Company/University
Retired

Personal Profile:

Mainly retired from Eastman Kodak. (Of course, Kodak itself is now semi-retired. I don't think I had any influence in that.) I still write MATLAB code as I find something interesting, but I DON'T answer your questions, and I do NOT do homework. Your homework is YOUR problem, not mine. Do NOT e-mail me with your homework problems or student projects. When I'm not doing something with MATLAB, you might find me playing bridge.

Professional Interests:
Bridge, MATLAB, numerical analysis, mathematical modeling

 

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Files Posted by John View all
Updated   File Tags Downloads
(last 30 days)
Comments Rating
16 Oct 2014 movingstd(x,k,windowmode) A (fast) windowed std on a time series Author: John D'Errico movingavg, standard deviation, std, window, filter 165 18
  • 4.75
4.8 | 12 ratings
14 Oct 2014 HPF - a big decimal class High precision floating point arithmetic, a new class written in MATLAB Author: John D'Errico hpf, multiple precision, big decimal, floating point, arithmetic, mathematics 83 20
  • 5.0
5.0 | 9 ratings
23 May 2014 Screenshot A suite of minimal bounding objects Suite of tools to compute minimal bounding circles, rectangles, triangles, spheres, incircles, etc. Author: John D'Errico miminum, bound, bounding, circle, rectangle, triangle 97 18
  • 4.71429
4.7 | 7 ratings
29 Apr 2014 polyfitn Polynomial modeling in 1 or n dimensions Author: John D'Errico polyfit, modeling, regression, linear regression, approximation, function 316 43
  • 4.96
5.0 | 25 ratings
29 Apr 2014 Screenshot SLM - Shape Language Modeling Least squares spline modeling using shape primitives Author: John D'Errico spline, splines, cubic, hermite, breaks, knots 186 103
  • 5.0
5.0 | 52 ratings
Comments and Ratings by John View all
Updated File Comments Rating
27 Oct 2014 Gaussian elimination with partial pivoting This code will perform the Gaussian elimination with partial pivoting for any square matrix. Author: Timothee

Of course, this is a homework assignment. NOBODY should actually use it for real work. PERIOD.

Instead, use backslash, solving the linear system of equations:

A*x = b

as

x = A\b;

Note that backslash works for square or non-square systems. It will be far more efficient than the homework assignment found in this submission here.

The help is poor in this code, essentially, non-existent. The only thing I like about the code is the fact that it has internal comments that explain (briefly) what each block of code does.

24 Oct 2014 Surface Fitting using gridfit Model 2-d surfaces from scattered data Author: John D'Errico

Evgheny - If you seriously need to fit such a surface in spherical coordinates, I might be able to help you out with a separate, un-posted toolbox that is capable of fitting a surface in spherical coordinates. You would need to contact me directly.

21 Oct 2014 Log of factorial of large numbers computes log10 of the factorial Author: Yvan Lengwiler

For those who don't want to remember the use of gammaln as implemented inside, this adds a few extras too. It is complete, with good help.

20 Oct 2014 A suite of minimal bounding objects Suite of tools to compute minimal bounding circles, rectangles, triangles, spheres, incircles, etc. Author: John D'Errico

Hi Tom,

The problem is as you point out, that the insphere code uses a dot product to find the distance to each facet. Then it is a simple call to linprog, with one slack variable for each facet.

A similar idea for edges though trips up becasue each edge has two normals. So then the distance to each edge is now the sqrt of the sum of squares of a pair of dot products. While I can avoid the sqrt, such a formulation would involve quadratic equality constraints for each slack variable. Clearly this is not solvable by linprog, or even quadprog. Fmincon would be needed, so a bit more nasty of a problem using a similar formulation to the one in insphere. Certainly one could use the existing insphere code to find decent starting values for such an iterative solution, but it is still a bit more work.

I'll need to think if there is another scheme that might apply.

John

16 Oct 2014 movingstd(x,k,windowmode) A (fast) windowed std on a time series Author: John D'Errico

Uploaded a new version to replace strmatch

Comments and Ratings on John's Files View all
Updated File Comment by Comments Rating
29 Oct 2014 nearestSPD Finding the nearest positive definite matrix Author: John D'Errico Ahmed

24 Oct 2014 putvar, uigetvar Move (get or put) variable(s) directly between a function workspace and the base workspace Author: John D'Errico Taylor

Very nice. Would love to see (1) an option in putvar (e.g. '-all') telling it to pass all variables, and (2) an option in putvar (e.g. '-struct',structname) telling it to pass the specified variable(s) inside a specified struct (structname in my example).

24 Oct 2014 inpaint_nans Interpolates (& extrapolates) NaN elements in a 2d array. Author: John D'Errico Roth, Jan-Philipp

This has saved my day. Thank you!

24 Oct 2014 Surface Fitting using gridfit Model 2-d surfaces from scattered data Author: John D'Errico D'Errico, John

Evgheny - If you seriously need to fit such a surface in spherical coordinates, I might be able to help you out with a separate, un-posted toolbox that is capable of fitting a surface in spherical coordinates. You would need to contact me directly.

23 Oct 2014 Surface Fitting using gridfit Model 2-d surfaces from scattered data Author: John D'Errico Evgheny

Thanks, function does do its job great!

Does anyone know alternative of this function for closed surface (sphere-like).
If I try this function with spherical coordinates, it works fine, but there are problems with the seam (line of joint)

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