Rank: 1263 based on 124 downloads (last 30 days) and 8 files submitted
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Christos Saragiotis

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King Abdullah University of Technology and Science

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Files Posted by Christos Saragiotis View all
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(last 30 days)
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01 Jul 2011 Screenshot Plotstack A plot utility, to plot graphs one over the other (or one next to the other vertically) Author: Christos Saragiotis measurement, demo, visualization, signal processing, plotting, figure 6 0
01 Jun 2010 Screenshot Peaks picking Finds peaks or troughs in a vector o 2-D matrix. Author: Christos Saragiotis data exploration, statistics, general tools, local, maxima, minima 17 1
  • 2.0
2.0 | 2 ratings
12 Apr 2010 Screenshot Graphical convolution animation Shows graphically the stages of discrete convolution for any two 1-D signals (educational tool). Author: Christos Saragiotis signal processing, convolution, graphic, education, discrete 20 0
04 Dec 2008 Lomb normalized periodogram Both functions calculate the Lomb-Scargle periodogram (aka Gauss-Vanicek/Least-squares spectrum) Author: Christos Saragiotis signal processing, earth science, transforms, lomb, least squares spectru..., spectrum 33 8
  • 4.2
4.2 | 6 ratings
29 Oct 2008 Fresnel integrals Calculates FresnelC, FresnelS integrals and their variations (C_1, C_2 and S_1 and S_2) Author: Christos Saragiotis fresnel, calculate, values, integrals, real values, vector 12 5
  • 3.0
3.0 | 3 ratings
Comments and Ratings by Christos Saragiotis View all
Updated File Comments Rating
23 Jan 2014 cprintf - display formatted colored text in the Command Window Displays sprintf-formatted strings in the Command Window using the specified color/underline style Author: Yair Altman

This is a really good submission, thanks!

I was able to add a predefined style 'Warnings' by
a. adding a 'Warnings' entry in the validStyles cell (after the 'Errors' entry) in function processStyleInfo,
b. changing the subsequent 'elseif mathces < 8' to 'elseif matches < 9' and
c. changing the following 'requestedColor = colors(matches-7,:);' to 'requestedColor = colors(matches-8,:);'.

It seems to be working fine so far.

30 Aug 2010 Fresnel integrals Calculates FresnelC, FresnelS integrals and their variations (C_1, C_2 and S_1 and S_2) Author: Christos Saragiotis

John,

thank you very much for your comments and the time you spent on thoroughly checking this function.

I will try to incorporate your suggestions, when I find some time

25 Aug 2010 mgrep Returns the names of all m-files in a directory or directory tree that contain a search string. Author: John D'Errico

23 Aug 2010 Fresnel integrals Calculates FresnelC, FresnelS integrals and their variations (C_1, C_2 and S_1 and S_2) Author: Christos Saragiotis

Dear William,

1. Regarding the "slowness issue":

This function is in fact FASTER than the submissions by Telasula and Barrows (btw Barrowes' submission is not something you can run, unless you correct it).

For example for an input of 200,000 samples, in my machine I get:
Barrows: 5.5 sec, Telasula: 3.1 sec, this function: 1.8 sec

This function is indeed slower than Barrowes' and Talasula's ones when you have inputs with very few samples (say 20 samples or so) but in that case the time of execution is of the order of msec. I think that 3 msec vs. 0.3 msec is not a waste of anyone's time.

2. Regarding the "accuracy issue":

Abramowitz's and Stegun's tables are accurate to the 10th decimal. Interpolation for other values was not my idea it was Abramowitz's and Stegun's idea. The accuracy of the interpolation was commented in the description of the file above. I don't see how your "findings" on the accuracy contribute anything new. By the way, what is the accuracy of Barrowes' or Telasula's submissions?

In my opinion it is very unfortunate that you gave a bad rating based
- on something which doesn't hold ("slowness") and
- on a limitation ("accuracy") which is however stated in both the description and the help of the function.

21 Jul 2010 LinkTopAxisData Adds a linked second x axis to a plot Author: Tim Richards

Good job. Two comments

Comment 1: I think it is a good idea to change lines 46 and 49 as follows:
(46) temp=[TopTickPositions(:), TopTickLabels(:)];
(49) temp = sortrows(temp);
This will allow users to enter either row or column vectors (or both) for the ticks and labels.

Comment 2 (regarding the bug that Thierry reported):
It can be fixed if line 50 is replaced by
temp(diff(temp(:,1))==0,:) = [];

Comments and Ratings on Christos Saragiotis' Files View all
Updated File Comment by Comments Rating
21 Nov 2014 Lomb normalized periodogram Both functions calculate the Lomb-Scargle periodogram (aka Gauss-Vanicek/Least-squares spectrum) Author: Christos Saragiotis David Verrelli

Erratum: my previous post indicated the default MACC=4. That was the value used by Press et al. However, Saragiotis used MACC=10 in his code (which I then used as the baseline).

14 Nov 2014 Lomb normalized periodogram Both functions calculate the Lomb-Scargle periodogram (aka Gauss-Vanicek/Least-squares spectrum) Author: Christos Saragiotis David Verrelli

ACCURACY COMMENTS
There are potential problems with the technique used to eliminate duplicates as consideration has not been given that the duplicate time values might be associated with different values of "x".
Hence comparisons of accuracy or timing between these m-files and alternative routines needs to be careful of different processing of duplicate input data points.

On another matter, it would also be advantageous to open the parameter MACC to the user to choose a value. As it stands, errors from the fast algorithm could be of order 2% (with limited testing) using the default MACC=4 [following Press et al.]. However, the discrepancy can be reduced by a factor of circa 100 (to an error of order 0.02%) by increasing MACC to 100; while this does reduce the speed of the "fast" algorithm, it remained quicker than the "slow" algorithm (in limited testing), and therefore also remained quicker than the two older routines from Shoelson and Savransky respectively.

14 Nov 2014 Lomb normalized periodogram Both functions calculate the Lomb-Scargle periodogram (aka Gauss-Vanicek/Least-squares spectrum) Author: Christos Saragiotis David Verrelli

SPEED COMMENTS
For me, on an old PC (Intel Core2 Duo E8500 @ 3.16/3.17 GHz, 8 GB RAM, Win7 64bit) both of these algorithms are so far (with limited testing) significantly faster than the alternatives of Brett Shoelson (File ID: #993) and Dmitry Savransky (File ID: #20004).
FOR EXAMPLE, with a data set of 4403 data points (with no time duplicates):
Shoelson ~ 69 s
Shoelson (with processing for duplicates) ~ 84 s
Savransky ~ 93 s
Saragiotis (slow) ~ 10.5 s
Saragiotis (fast) ~ 0.2 s
Saragiotis (fast, with MACC=100) ~ 2.3 s

22 Oct 2014 Laplace random variables This function generates random numbers distributed according to the Laplace distribution Author: Christos Saragiotis li ming

good

14 Nov 2013 Lomb normalized periodogram Both functions calculate the Lomb-Scargle periodogram (aka Gauss-Vanicek/Least-squares spectrum) Author: Christos Saragiotis D

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