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.

See my CL homepage for my teaching there.

Research interests

Compressed Sensing, Signal Processing, Sampling Theory, Inverse Problems, Computational Mathematics.

See my CL homepage for my research on wireless comms.


  • Fast C++ MEX (Matlab) Walsh-Hadamard transform with support for sequency and natural ordering, multi-core/multi-cpu (via OpenMP) and also complex values. It is orders of magnitute faster than Matlab's fwht() function.
    Download v1.2, May 2014. Package includes:
    - 64 bit binaries for Linux, MacOSX and Windows
    - C++ source (see hadtr.cpp for compilation instructions)
    - Matlab wrappers for the 2D transform and unitary 1D and 2D transforms.
  • 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.