Dr Bogdan Roman


I am a Research Associate in the Applied Functional and Harmonic Analysis group at DAMTP. I am also a Visiting Research Fellow at the Computer Laboratory department, and an Academic Fellow and Director of Studies for Computer Science at Homerton College.

Tel: +44 1223 760403
Email: abr28 [at] cam.ac.uk



Siemens validated in practice, using a modified MRI machine, the asymptotic sparsity, asymptotic incoherence and high resolution concepts introduced by our work (see Breaking the coherence barrier: A new theory for compressed sensing and also On asymptotic structure in compressed sensing). From their results and conclusion:

“The image resolution has been greatly improved [...]. Current results practically demonstrated that it is possible to break the coherence barrier by increasing the spatial resolution in MR acquisitions. This likewise implies that the full potential of the compressed sensing is unleashed only if asymptotic sparsity and asymptotic incoherence is achieved.”

Their work Novel Sampling Strategies for Sparse MR Image Reconstruction was published in May 2014 in the Proceedings of the International Society for Magnetic Resonance in Medicine.

The major effects and benefits of these concepts are summarised on Page 4 of our latest work On asymptotic structure in compressed sensing, which also includes a large number of example experiments.


Part III course on Compressed Sensing. For my teaching and supervising at the Computer Lab, please see my CL homepage.

Research interests

Compressed sensing, signal processing, sampling theory, inverse problems, computational mathematics. For my research on wireless comms, please see my CL homepage.


  • (Very) Fast C++ MEX Hadamard (Walsh-Hadamard) transform with support for sequency and natural ordering, multi-core/multi-cpu and also complex values. Orders of magnitude faster than Matlab's fwht() function.
    Download v1.3, Oct 2014. Includes 64bit binaries for Linux, MacOSX and Windows, and Matlab wrappers for 1D and 2D transforms, unitary and non-unitary.
  • Compiling MEX files directly from Matlab seamlessly under Windows using GCC (MinGW64). This should normally work with most C/C++ MEX files that work under Linux. You also won't need to carry or distribute the std runtime .DLLs from MingW/Cygwin.
    Download this mexopts.bat file and place it in %USERPROFILE%\AppData\Roaming\Mathworks\MATLAB\R2014a\. See more instructions and details inside the downloaded mexopts.bat file (see also this StackExchange answer).
  • MacOH. Automated tool for stress testing Mac machines to reveal throttling or overheating. It downloads all needed tools, starts benchmarks, monitors CPU temperature and frequency, and plots them versus time (sample output). First created as a personal test tool. It can do CPU and GPU tests (Prime95, x264, GpuTest, user defined).
    Get it on GitHub.


I sometimes create and collect probability theory questions and puzzles, some which you can find below. They are short, yet not all trivial. I hope that trained probabilists still find some of them challenging.

Probability Questions (PDF)

I also use them in my undergraduate teaching and am always interested in alternative solutions and extensions (or new questions) so if you have any then I'd love to hear from you.