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Time Warps, from Algebra to Algorithms [article]

Sam van Gool, Adrien Guatto, George Metcalfe, Simon Santschi
2021 arXiv   pre-print
In particular, continuous endomaps of the discrete time scale, or time warps, can be used to quantify the growth of information in the course of program execution.  ...  In this paper, we study the algebraic structure of time warps, and prove that their equational theory is decidable, a necessary condition for their use in real-world compilers.  ...  ,f k of time warps f 1 , . . . , f k , such that t (p) < p, where t is the time warp obtained from t by mapping each x i to f i .  ... 
arXiv:2106.06205v2 fatcat:gsis3t5q2rfedivegjodp2eydq

Joint geometric and photometric direct image registration based on Lie algebra parameterization

Chenxi Li, Zelin Shi, Yunpeng Liu
2016 Infrared Technology and Applications, and Robot Sensing and Advanced Control  
Experimental results show that our algorithm is more robust to lighting changes and has higher registration accuracy compared to previous algorithms.  ...  J is the image gradient of , w J is the Jacobian due to a pixel warping function, () w      H J 0 J x x J J J J 0 x .  ...  While the iteration times of ADESM algorithm increases fast as is far away from 1, the iteration times of our proposed algorithm almost stays constant.  ... 
doi:10.1117/12.2246720 fatcat:wpmojq3rqncwvnucht6i2byope

Synchronization for dynamic blending of motions [article]

Stéphane Ménardais, Richard Kulpa, Franck Multon, Bruno Arnaldi
2004 Proceedings of the 2004 ACM SIGGRAPH/Eurographics symposium on Computer animation - SCA '04  
We propose an advanced time warping algorithm to synchronize such motions. This algorithm uses the sequence of support phases of the motions.  ...  In this paper we present a new real-time synchronization algorithm. In dynamic environments, motions need to be continuously adapted to obtain realistic animations.  ...  Acknowledgements We would like to thank gratefully Stéphane Donikian and Marwan Badawi for their helpful reviews of this paper and their suggestions.  ... 
doi:10.2312/sca/sca04/325-335 fatcat:52xwly5e3vc6hpo7rrrwjbzxti

Projective Tracking Based on Second-Order Optimization on Lie Manifolds

Guangwei Li, Yunpeng Liu, Jian Yin, Zelin Shi
2008 2008 Chinese Conference on Pattern Recognition  
The algorithm on the vector space has more limitations when it concerns the nonlinear projective warps.  ...  The comparative experiments with the algorithm based on the vector space and the Gauss-Newton algorithm based on the Lie algebra parameterization validate the feasibility and high effectiveness of our  ...  We randomly perturbed white Gaussian noise of a certain standard variance σ from one pixel to ten pixels and fitted for the projective warp parameters that these perturbed points define (for each standard  ... 
doi:10.1109/ccpr.2008.46 fatcat:kt36eysufjamfmwjvm4zzyhkmq

Warp-Drive Quantum Computation [article]

Mikio Nakahara, Juha J. Vartiainen, Yasushi Kondo, Shogo Tanimura, and Kazuya Hata
2004 arXiv   pre-print
This gate W sends U_ alg to another algorithm WU_ alg which is executable in a shorter time than U_ alg. We call this technique warp-drive.  ...  This allows us to reduce the execution time of a quantum algorithm U_ alg further by adding an extra gate W to it.  ...  When applied to two-qubit Grover's algorithm in the NMR experiment the execution time is found to be halved along with a reduction in the number of the gate pulses from 10 to 4.  ... 
arXiv:quant-ph/0411153v2 fatcat:oqh2g2vppfdt7pm6434db2jnle

Sgap: Towards Efficient Sparse Tensor Algebra Compilation for GPU [article]

Genghan Zhang, Yuetong Zhao, Yanting Tao, Zhongming Yu, Guohao Dai, Sitao Huang, Yuan Wen, Pavlos Petoumenos, Yu Wang
2022 arXiv   pre-print
We achieve 1.6x - 2.3x speedup on the algorithm tuned with atomic parallelism.  ...  Atomic parallelism captures the flexible reduction semantics to systematically analyze the optimization space of sparse-dense hybrid algebra on GPU.  ...  Algebra Compilation for GPU method for SpMM merging workloads from different warps to reuses loaded sparse matrix.  ... 
arXiv:2209.02882v1 fatcat:b5ozokczovg5pfnqoufwlzetvq

Optimization on Lie Manifolds and Projective Tracking

Li Guangwei, Liu Yunpeng, Yin Jian, Shi Zelin
2008 2008 International Conference on Computer Science and Software Engineering  
The algorithm on the vector space has more limitations when it concerns the nonlinear projective warps.  ...  The new method relies on the differential geometry of Lie manifolds and the underlying connections between Lie groups and their associated Lie algebras.  ...  We randomly perturbed the four corner points of the template 1000 times with additive white Gaussian noise of a certain standard variance from one pixel to ten pixels and fitted for the projective warp  ... 
doi:10.1109/csse.2008.1241 dblp:conf/csse/GuangweiYJZ08 fatcat:6gic6vemnzbyzhzgfjp4nhc2xm

Comparison of Analytic and Algebraic Methods for Motion-Compensated Cone-Beam CT Reconstruction of the Thorax

S. Rit, D. Sarrut, L. Desbat
2009 IEEE Transactions on Medical Imaging  
The second one is algebraic: the system of linear equations is generated using a new algorithm for the projection of deformable volumes and solved using the Simultaneous Algebraic Reconstruction Technique  ...  The first one is analytic; it is heuristically adapted from the method of Feldkamp, Davis, and Kress (FDK).  ...  ACKNOWLEDGMENT The authors would like to thank Prof. M. van Herk for critical reading and for permitting the use of the viewer developed at The Netherlands Cancer Institute.  ... 
doi:10.1109/tmi.2008.2008962 pmid:19211348 fatcat:izzqc4zw3fgoznpott5cnxi4ei

Padding Free Bank Conflict Resolution for CUDA-Based Matrix Transpose Algorithm

Ayaz ul Hassan Khan Khan, Mayez Al-Mouhamed, Allam Fatayer, Anas Almousa, Abdulrahman Baqais, Mohammed Assayony
2014 International Journal of Networked and Distributed Computing (IJNDC)  
The proposed algorithms have comparable execution times with the NVIDIA SDK bank conflict -free matrix transpose implementation.  ...  We have also applied the proposed transpose algorithm to recursive gaussian implementation of NVIDIA SDK and achieved about 6% improvement in performance.  ...  We have also applied the proposed transpose algorithm to recursive gaussian implementation of NVIDIA SDK and achieved about 6% improvement in performance.  ... 
doi:10.2991/ijndc.2014.2.3.2 fatcat:q4t3uohombc2hb626aoj6i6soe

An intrinsic characterization of spherically symmetric spacetimes

Joan Josep Ferrando, Juan Antonio Sáez
2010 Classical and quantum gravity  
We give the necessary and sufficient (local) conditions for a metric tensor to be a non conformally flat spherically symmetric solution.  ...  The algebraic classification of the space-time symmetric tensors was given by Churchill [11] , and since the sixties a lot of work has been devoted to studying the Ricci tensor from an algebraic point  ...  Further, we give the algorithm to determine the canonical elements of a spherically symmetric spacetime from the Riemann tensor.  ... 
doi:10.1088/0264-9381/27/20/205024 fatcat:3x4plvqvhfclfcwsz3qucvbey4

Accelerating Iterative SpMV for Discrete Logarithm Problem Using GPUs [article]

Hamza Jeljeli
2014 arXiv   pre-print
Most of the fast algorithms used to solve such systems --- e.g., the conjugate gradient or the Lanczos and Wiedemann algorithms --- iterate a product of the corresponding sparse matrix with a vector (SpMV  ...  The proposed SpMV implementation contributed to solving the discrete logarithm problem in GF(2^619) and GF(2^809) using the FFS algorithm.  ...  This linear algebra step is a serious limiting factor in such algorithms.  ... 
arXiv:1209.5520v4 fatcat:yucl3rzthfarxlbfxuhwz4tcdm

Accelerating Iterative SpMV for the Discrete Logarithm Problem Using GPUs [chapter]

Hamza Jeljeli
2015 Lecture Notes in Computer Science  
Most of the fast algorithms used to solve such systems -e.g., the conjugate gradient or the Lanczos and Wiedemann algorithms -iterate a product of the corresponding sparse matrix with a vector (SpMV).  ...  The proposed SpMV implementation contributed to solving the discrete logarithm problem in GF(2 619 ) and GF(2 809 ) using the FFS algorithm.  ...  This linear algebra step is a serious limiting factor in such algorithms.  ... 
doi:10.1007/978-3-319-16277-5_2 fatcat:442ccuiv2baqhjkfqsygdc67pm

A Synchronization-Free Algorithm for Parallel Sparse Triangular Solves [chapter]

Weifeng Liu, Ang Li, Jonathan Hogg, Iain S. Duff, Brian Vinter
2016 Lecture Notes in Computer Science  
and 2.14 times in double precision.  ...  The sparse triangular solve kernel, SpTRSV, is an important building block for a number of numerical linear algebra routines.  ...  The research leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement number 671633.  ... 
doi:10.1007/978-3-319-43659-3_45 fatcat:pziplb5ivzfsvcgt6hzfslenfi

An intrinsic characterization of 2 + 2 warped spacetimes

Joan Josep Ferrando, Juan Antonio Sáez
2010 Classical and quantum gravity  
We give several equivalent conditions that characterize the 2+2 warped spacetimes: imposing the existence of a Killing-Yano tensor A subject to complementary algebraic restrictions; in terms of the projector  ...  The warped products correspond to two of these invariant classes. The more degenerate class is the set of product metrics which are also studied from an invariant point of view.  ...  Then we arrive to the algorithm that we present below as a flow chart.  ... 
doi:10.1088/0264-9381/27/20/205023 fatcat:dhki6lstfjewfoj57y6az267ja

GPU-Accelerated Sparse Matrix-Matrix Multiplication by Iterative Row Merging

Felix Gremse, Andreas Höfter, Lars Ole Schwen, Fabian Kiessling, Uwe Naumann
2015 SIAM Journal on Scientific Computing  
The main kernel merges small numbers of sparse rows at once using sub-warps of threads to realize an early compression effect which reduces the overhead of global memory accesses.  ...  While special algorithms may be advantageous for special types of graphs or matrices, a fast and general SpGEMM implementation turns out to be desirable for abstract programming and high-level languages  ...  The authors would like to thank Weifeng Liu for providing data to allow comparison with his work [31] .  ... 
doi:10.1137/130948811 fatcat:rvjvw53itfbhxiyxgkeh4n3ko4
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