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RESEARCH
COURSES
PUBLICATIONS
RESUME
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RESEARCH
My core research area is in high performance computing with a focus on the
application of combinatorial and machine learning methods
in solving sparse linear systems, large scale data
analysis and bioinformatics. Current research projects include:
Multimethod Solvers
Design of multimethod solvers involves the development of robust and scalable algorithms for
sparse linear systems by leveraging the strength of existing linear solvers. We developed the composite multimethod
solver, where the linear system is applied to a sequence of solvers, and
the adaptive multimethod solver, where
linear solvers are dynamically selected to match evolving linear system
properties.
Related Publications
(With: Dinesh
Kaushik,
Lois Curfman McInnes,
Boyana Norris,
Padma Raghavan)
Machine Learning for Linear
Solvers
Linear solvers are designed to cater to different solution
requirements, and their
performance depend on
the properties of the linear systems being solved. Matching linear solvers to problem
characteristics can produce near optimal performance. However, given the wide variety of linear solvers, the
algorithmic options explode combinatorially. We use machine learning techniques to select
"good" solvers according to linear system characteristics.
Related Publications
(With: Victor
Eijkhout
,Yoav Freund,
Erika Fuentes,
David Keyes,
Brice Toth)
Automatic Differentiation
Automatic differentiation is based on evaluating the exact
derivatives of functions by using the chain rule,
in order to avoid the inevitable numerical errors of Taylor's method. Function sequences in the chain rule are
represented as directed acyclic graphs. Therefore, algorithms for
automatic differentiation can be derived through
combinatorial techniques. Our work involves the optimization of
Hessian (second order derivative) calculation through
detecting symmetry in the computational graph.
Related Publications
(With: Paul
Hovland)
Applications of
Graph
Embedding
Graph embedding is used to arrange vertices and
edges in an
aesthetically pleasing pattern on a two dimensional space. Extending this
concept to placement in an n-dimensional space, we use embedding
algorithms
to optimize data layout in multicore architectures and in improving the
accuracy of supervised and unsupervised clustering.
Related Publications
(With: Anirban Chaterjee,
Padma Raghavan,
Archana Vishwanathan)
Protein Mediated DNA Folding
The propensity of DNA folding due to protein binding at
different sites of the chromatin is regulated by the density of solvent
molecules. Depending on the region of binding, the folding gives rise to
different loop patterns such as cycles, figures of eight, etc. This
project involves calculating solvent density through clustering and
enumerating a set of unique designs that will enable biologists to
quantitatively describe the structural
modications.
(With:
Wilma Olson,
Frank Pugh,
Padma Raghavan)
Large Scale Dynamic Networks
An important challenge in large scale
dynamic networks lie in designing effcient algorithms to calculate
properties of the graph. This project involves development of fast
algorithms to recompute graph
properties based only on the updates to the network at each time
step, and techniques for comparing different large-scale
networks.
(With:
Shweta Bansal,
Kelly Fermoyle,
Padma Raghavan)
COURSES OFFERED
LINKS TO SELECTED
PUBLICATIONS
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Robust Algorithms and Software for Parallel PDE-Based Simulations,
S. Bhowmick, L.McInnes, B.Norris,
and P.Raghavan, Proceedings of HPC
2004, the
Twelfth Special Symposium on High Perfomance Computing at the 2004 Advanced Simulation Technologies Conference, Arlington, VA, April 18-22,
2004.
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Combinatorial Algorithms Enabling
Computational Science: Tales From the Front, S. Bhowmick, E.
Boman, K. Devine, A. Gebremedhin, B.Hendrickson, P.Hovland, T. Munson and A. Pothen, Journal of Physics: Conference Series, Vol 46, 2006
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