Rank: 5 based on 3409 downloads (last 30 days) and 59 files submitted
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John D'Errico

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43.236435, -76.93324

Personal Profile:

Retired from the Eastman Kodak Company, where I was an applied mathematician consulting typically on matters of curve fitting, modeling, and numerical analysis. I enjoy playing bridge, doing woodworking and woodturning, and going for walks. We have a sweet wire hair fox terrier. In my spare time I still like to use Matlab.

Professional Interests:
Numerical analysis, mathematical modeling

 

Watch this Author's files

 

Files Posted by John View all
  • 1 - 5 of
  • 59
Updated   File Tags Downloads
(last 30 days) 		Comments Rating
26 Jan 2010 Published M-Files Variable Precision Integer Arithmetic Arithmetic with integers of fully arbitrary size. Arrays and vectors of vpi numbers are supported. Author: John D'Errico toolbox, projecte, rabin, biginteger, mersenne, data type 158 34
  • 4.75
4.8 | 22 ratings
22 Jan 2010 Published M-Files SLM - Shape Language Modeling Least squares spline modeling using shape primitives Author: John D'Errico shape, free knots, interpolation, spline, splines, slm 168 21
  • 5.0
5.0 | 14 ratings
13 Jan 2010 Screenshot insphere Inscribed sphere, entirely inside the facets of a 3-d convex hull Author: John D'Errico circumsphere, convex hull, computational geometr..., sphere, insphere 71 1
  • 5.0
5.0 | 1 rating
17 Dec 2009 Published M-Files Polyfitn N-d polynomial regression model Author: John D'Errico surface, linear regression, polynomial, fit, modeling, interpolation 184 34
  • 4.5
4.5 | 22 ratings
22 Nov 2009 binomfactors Returns a factored form for very large binomial coefficients Author: John D'Errico vpi, nchoosek, factors, factor, binomial coefficient, binomial 22 0
Comments and Ratings by John View all
  • 1 - 5 of
  • 165
Updated File Comments Rating
03 Feb 2010 savehold: Run the 'hold on' command and save its state for possible restoration A small utility encapsulating the call to 'ishold', 'hold on' and a restortion of the hold state. Author: Petr Pošík

I'll admit, this is a simple thing. Nothing dramatic here, with only a couple of lines of simple code. But it might make your own code just a wee bit simpler to write and to read later on. And simple, modular code is always good. If holds on plots are something you do often, then you may like this utility.

I like the help. An H1 line, etc. The 5 rating is a tip of my hat to the author.
03 Feb 2010 Q function Computes the value of the Q function Author: Micu

Oh, I just had to open this up to see what was inside. This is all I found. No help at all. No H1 line. No error checking. Just one short piece of code that does something trivial. Here it is. I'll save you all the waste of time to download it.

function Q=Q_Function(x)
Q=erfc(x/sqrt(2))/2;

When you write software to give away to others, there must be some reason to do so. Is your function especially useful? Does it do something that others will not be able to do? Does it make their lives in MATLAB easier for some reason?

A good submission should do one of two things. It should teach others something of value, or it should provide utility that was lacking previously in MATLAB. This submission does nothing to further either goal.

There is no hint here of what the function does. The Q function? Yeah, right. There are lots of things in mathematics/statistics that have the letter Q associated with them.

As far as teaching goes, all this teaches other people is how NOT to write software for public consumption.
02 Feb 2010 SLM - Shape Language Modeling Least squares spline modeling using shape primitives Author: John D'Errico

Kay - While I would like to help you (and the many others who have requested confidence intervals) and provide confidence intervals for this tool, they would not be valid much of the time. Whenever any inequality constraints are involved, the standard methods for confidence intervals for a linear regression become inappropriate. And many of the most useful aspects of this tool involve inequality constraints. Worse, things become nastier yet if free knots are estimated.

While I could, in theory, use more sophisticated techniques to provide confidence intervals, these techniques would become quite time consuming.

John
27 Jan 2010 setPrompt - Set the Command Window prompt Sets the Command Window prompt to the specified string Author: Yair Altman

I would only add (as one of the people who reported a Mac problem) that I saw the problem in release R2007b, on an old mac with probably an old copy of Java. For the rest of you, rest assured that this appears to be a well written, well documented, professional piece of code.
26 Jan 2010 Variable Precision Integer Arithmetic Arithmetic with integers of fully arbitrary size. Arrays and vectors of vpi numbers are supported. Author: John D'Errico

Thanks Ian. I've sent in an update to fix the legendresymbol bug. John
Comments and Ratings on John's Files View all
  • 1 - 5 of
  • 565
Updated File Comment by Comments Rating
07 Feb 2010 Variable Precision Integer Arithmetic Arithmetic with integers of fully arbitrary size. Arrays and vectors of vpi numbers are supported. Author: John D'Errico Fell, Harriet

06 Feb 2010 Inhull Efficient test for points inside a convex hull in n dimensions Author: John D'Errico Bellec, Pierre

Great code. I've used it for head segmentation in MRI. A simple intensity thresholding left lots of holes in the head, and that function filled them easily. It was a problem in low dimension (3) but quite high resolution (256*256*128). In any case, it saved me a lot of time and I really appreciate it.

02 Feb 2010 SLM - Shape Language Modeling Least squares spline modeling using shape primitives Author: John D'Errico D'Errico, John

Kay - While I would like to help you (and the many others who have requested confidence intervals) and provide confidence intervals for this tool, they would not be valid much of the time. Whenever any inequality constraints are involved, the standard methods for confidence intervals for a linear regression become inappropriate. And many of the most useful aspects of this tool involve inequality constraints. Worse, things become nastier yet if free knots are estimated.

While I could, in theory, use more sophisticated techniques to provide confidence intervals, these techniques would become quite time consuming.

John
31 Jan 2010 SLM - Shape Language Modeling Least squares spline modeling using shape primitives Author: John D'Errico Kay

can the program determine 95% cofidence interval of the estimated parameters?
31 Jan 2010 Inpainting nan elements in 3-d An extension of inpaint_nans to 3 dimensions Author: John D'Errico Georgina

Top Tags Applied by John
  • 1 - 5 of
  • 260
approximation, interpolation, computational geometry, matrices, minimum
Files Tagged by John View all
  • 1 - 5 of
  • 61
Updated   File Tags Downloads
(last 30 days) 		Comments Rating
26 Jan 2010 Published M-Files Variable Precision Integer Arithmetic Arithmetic with integers of fully arbitrary size. Arrays and vectors of vpi numbers are supported. Author: John D'Errico toolbox, projecte, rabin, biginteger, mersenne, data type 158 34
  • 4.75
4.8 | 22 ratings
22 Jan 2010 Published M-Files SLM - Shape Language Modeling Least squares spline modeling using shape primitives Author: John D'Errico shape, free knots, interpolation, spline, splines, slm 168 21
  • 5.0
5.0 | 14 ratings
13 Jan 2010 Screenshot insphere Inscribed sphere, entirely inside the facets of a 3-d convex hull Author: John D'Errico circumsphere, convex hull, computational geometr..., sphere, insphere 71 1
  • 5.0
5.0 | 1 rating
17 Dec 2009 Published M-Files Polyfitn N-d polynomial regression model Author: John D'Errico surface, linear regression, polynomial, fit, modeling, interpolation 184 34
  • 4.5
4.5 | 22 ratings
22 Nov 2009 binomfactors Returns a factored form for very large binomial coefficients Author: John D'Errico vpi, nchoosek, factors, factor, binomial coefficient, binomial 22 0
 

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