Rank: 585 based on 193 downloads (last 30 days) and 13 files submitted
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Adam Wyatt

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Company/University
University of Oxford
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51.759792, -1.256422

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Professional Interests:
Ultrafast laser metrology

 

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Files Posted by Adam View all
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(last 30 days)
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04 Mar 2009 Screenshot Hankel Transform Routine to perform a QDHT with no limit on data size or transform order (other than memory constrain Author: Adam Wyatt chemistry, physics, qdht bessel quasi dis... 22 3
  • 4.0
4.0 | 2 ratings
22 Jan 2009 Screenshot SPIDER simulation Simulates spectral phase interferometry for direct electric-field reconstruction (SPIDER). Author: Adam Wyatt chemistry, physics, spider, spectral, phase interferometry, direct electricfield 21 3
  • 4.0
4.0 | 1 rating
01 Aug 2008 Screenshot Stationary phase approximation for performing Fourier Transforms Performs a Fourier Transform of a function using the stationary phase approximation Author: Adam Wyatt integration, stationary phase appr..., fourier transform, timebandwidth 17 0
07 Jul 2008 Screenshot Frequency-resolved optical gating (FROG) Generates a FROG trace from a pulse and gate field in time and rconstructs these fields. Author: Adam Wyatt chemistry, physics, frog, frequency, resolved, optical 22 4
  • 5.0
5.0 | 5 ratings
18 Feb 2008 quadvgk G7-K15 adaptive quadrature on vector-valued functions Author: Adam Wyatt integration, apative, quadrature, vector, valued, functions 11 4
  • 4.5
4.5 | 3 ratings
Comments and Ratings by Adam View all
Updated File Comments Rating
18 Apr 2012 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

Great.

Suggestion - can you add support for bold text to. I presume its doable since the command window already utilizes bold text.

13 Apr 2011 Calculate Wigner distribution Calculates the 2D Wigner distribution of a complex function. Author: Adam Wyatt

You have to think what you are doing - given data of length N, the Wigner distribution is N^2, so clearly with N=10^5, N^2 = 10^10 - you're not going to ever be able to make such a Wigner distribution.

However, it is possible that you do not need the Wigner distribution over the whole temporal and spectral domains. Unfortunately I have not implemented this yet.

13 Apr 2011 Hankel Transform Routine to perform a QDHT with no limit on data size or transform order (other than memory constrain Author: Adam Wyatt

The example given in the code does not scale the amplitudes of the angular distribution because it is not necessary (since it is only necessary to multiply by a phase factor and so the scaling required will be undone again before transforming back). However, strictly speaking this should be done as follows:

H = hankel_matrix(0, rmax, samples);
HT = @(f) (H.T*(f./H.JR)).*H.JV;
IHT = @(F) (H.T*(F./H.JV)).*H.JR;

Note that two scaling vectors are supplied:

H.JR
H.JV

Therefore I agree that the example is misguiding from a physical point of view, but not computationally, but it is not incomplete.

Note that there is a difference between the Hankel transform (HT) and the quasi discrete Hankel transform (qDHT). This code provides a way of performing the qDHT and the scaling vectors to turn it into an accurate estimation of the HT.

Indeed there is a factor of 2pi, but as stated this does depend on the definition of the HT used - so long as f = IHT(HT(f)), its all good. So using the definition consistent with the code:

HT{exp(-br^2)} = pi/b * exp{-k^2/(2*b)];

Further details can be found in the references given in the code.

13 Apr 2011 GUI Layout Toolbox Layout management objects for MATLAB GUIs Author: Ben Tordoff

Excellent work!

Comments and Ratings on Adam's Files View all
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21 May 2013 Frequency-resolved optical gating (FROG) Generates a FROG trace from a pulse and gate field in time and rconstructs these fields. Author: Adam Wyatt Lin, Jipeng

21 Jul 2012 Calculate Wigner distribution Calculates the 2D Wigner distribution of a complex function. Author: Adam Wyatt Nelatury, Charles

02 Jun 2012 Calculate Wigner distribution Calculates the 2D Wigner distribution of a complex function. Author: Adam Wyatt scheinfeild, michael

your delay is always half of the signal
the matrix can be too large
for chirp test the max locations should be at phase 2*f*b*t but the max is alwayes at the center

02 Jun 2012 Calculate Wigner distribution Calculates the 2D Wigner distribution of a complex function. Author: Adam Wyatt scheinfeild, michael

09 Feb 2012 Frequency-resolved optical gating (FROG) Generates a FROG trace from a pulse and gate field in time and rconstructs these fields. Author: Adam Wyatt Byrnes, Steven

I wrote my own program, starting with this one. (You can find it posted under the same title as this one). I found this program to be a nice starting point to use. I found plenty of room for improvements and additions, but I don't remember finding any bugs that would noticeably impact the results.

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