Rank: 6 based on 2732 downloads (last 30 days) and 51 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
27 Feb 2013 Screenshot distance2curve Find the closest point on a (n-dimensional) curve to any given point or set of points Author: John D'Errico arclength, interpolant, distance, interpolation, curve, space curve 56 7
  • 5.0
5.0 | 4 ratings
02 Jan 2013 Inverse (integrated) gradient Vectorized & fully sparse 1-d, 2-d, & 3-d integrated gradients Author: John D'Errico integration, simpsons rule, gradient, cumulative, trapezoidal rule, numerical integration 23 5
  • 5.0
5.0 | 4 ratings
10 Dec 2012 HPF - a big decimal class High precision floating point arithmetic, a new class written in MATLAB Author: John D'Errico hpf, arithmetic, big decimal, floating point, multiple precision, mathematics 32 5
  • 5.0
5.0 | 6 ratings
06 Sep 2012 Screenshot Inhull Efficient test for points inside a convex hull in n dimensions Author: John D'Errico convex hull, inhull, hull, tsearch, tsearchn 47 33
  • 4.57143
4.6 | 22 ratings
16 Aug 2012 Screenshot IPDM: Inter-Point Distance Matrix An efficient and accurate Inter-Point Distance Matrix Author: John D'Errico distance, interpoint, distances, euclidean, metrics, nearest neighbor 53 11
  • 4.57143
4.6 | 7 ratings
Comments and Ratings by John View all
Updated File Comments Rating
27 Jun 2013 Surface blend by linear equations A solution for blending surfaces and curves by linear equations. Author: small

No help in here. No explanation of how to use it, or even any clear explanation of what it does. As it is, this is just a set of random lines of code, most of which are not that well written.

For example, looking inside, I see the lines:

ind=[1,0,0,0;
0,1,0,0;
0,0,1,0;
0,0,0,1;];

Perhaps the author should learn how to use the tools already in MATLAB, here for example, eye.m.

Without looking deeply into the code, I don't know if the rest of this loopy code can be improved as trivially. I'll bet it can, but I'm not going to invest that time.

I'd suggest the author learn how to comment their code. Learn how to write adequate help.

27 Jun 2013 Surface blend by linear equations A solution for blending surfaces and curves by linear equations. Author: small

17 Jun 2013 Surface Fitting using gridfit Model 2-d surfaces from scattered data Author: John D'Errico

Alejandro - while I would like to implement that capability one day in the future, that day may be a long time away before I find the time. Until then, all I can offer is to use a finer grid, which will mimic a higher order interpolant.

17 Jun 2013 Surface Fitting using gridfit Model 2-d surfaces from scattered data Author: John D'Errico

Dominik - Sorry, but no. You could use this tool to generate a gridded surface, then use interp2, to interpolate, but that is perhaps too much if you only wanted to interpolate a few scattered points.

06 Jun 2013 SLM - Shape Language Modeling Least squares spline modeling using shape primitives Author: John D'Errico

A long time ago, I wrote a tool that would take an existing spline, and rather than simply evaluate the first or last segments of the spline for extrapolation, I added a new segment that had all desired properties, like monotonicity, concavity, endpoint slope or value constraints, etc. Of course the new segments were fully consistent with the old end points of the spline and the shape at that point. If necessary to meet the specified constraints, I added several segments. The interface for this code was similar to that for SLM, with many possible property/value pairs for any possible shape.

I'll claim that this tool fully met with the SLM philosophy, in that it encouraged the user to explicitly specify information about the shape of the extrapolated curve. While I'd like to provide such a tool, more important in my opinion is to write a GUI wrapper for SLM.

To a large extent you can do that form of extrapolation already, when you first build the curve. Simply specify knots that go out as far as you need the curve to go. The knots need not always be tight up to the end points of the data. (That is the default for SLM, but you can choose your own knots.) This allows you to directly apply any pertinent shape information about that extrapolated region.

Comments and Ratings on John's Files View all
Updated File Comment by Comments Rating
30 Jun 2013 SLM - Shape Language Modeling Least squares spline modeling using shape primitives Author: John D'Errico SantiagoRojas

30 Jun 2013 inpaint_nans Interpolates (& extrapolates) NaN elements in a 2d array. Author: John D'Errico Han

21 Jun 2013 distance2curve Find the closest point on a (n-dimensional) curve to any given point or set of points Author: John D'Errico VanWeelden, Shaun

This file just saved me SO much time!! Thanks a million!

18 Jun 2013 Color name identification: fuzzycolor Efficient identification of color names for any RGB Author: John D'Errico Petrov, Lyuboslav

Very happy with results. Great Work!

17 Jun 2013 Surface Fitting using gridfit Model 2-d surfaces from scattered data Author: John D'Errico D'Errico, John

Alejandro - while I would like to implement that capability one day in the future, that day may be a long time away before I find the time. Until then, all I can offer is to use a finer grid, which will mimic a higher order interpolant.

Top Tags Applied by John
interpolation, curve, distance, modeling, regression
Files Tagged by John View all
Updated   File Tags Downloads
(last 30 days)
Comments Rating
27 Feb 2013 Screenshot distance2curve Find the closest point on a (n-dimensional) curve to any given point or set of points Author: John D'Errico arclength, interpolant, distance, interpolation, curve, space curve 56 7
  • 5.0
5.0 | 4 ratings
02 Jan 2013 Inverse (integrated) gradient Vectorized & fully sparse 1-d, 2-d, & 3-d integrated gradients Author: John D'Errico integration, simpsons rule, gradient, cumulative, trapezoidal rule, numerical integration 23 5
  • 5.0
5.0 | 4 ratings
10 Dec 2012 HPF - a big decimal class High precision floating point arithmetic, a new class written in MATLAB Author: John D'Errico hpf, arithmetic, big decimal, floating point, multiple precision, mathematics 32 5
  • 5.0
5.0 | 6 ratings
06 Sep 2012 Screenshot Inhull Efficient test for points inside a convex hull in n dimensions Author: John D'Errico convex hull, inhull, hull, tsearch, tsearchn 47 33
  • 4.57143
4.6 | 22 ratings
16 Aug 2012 Screenshot IPDM: Inter-Point Distance Matrix An efficient and accurate Inter-Point Distance Matrix Author: John D'Errico distance, interpoint, distances, euclidean, metrics, nearest neighbor 53 11
  • 4.57143
4.6 | 7 ratings

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