Listar por autoría "d9c4d9e8-fe2d-4256-989c-d128bf00a4b7"

Mostrando ítems 1-20 de 30

    • closedAccess   A Runtime System for Programming Out-of-Core Matrix Algorithms-by-Tiles on Multithreaded Architectures 

      Quintana-Ortí, Gregorio; Igual, Francisco D.; Marqués-Andrés, Mercedes; Quintana-Orti, Enrique S.; Van de Geijn, Robert A. ACM (2012-08)
      Out-of-core implementations of algorithms for dense matrix computations have traditionally focused on optimal use of memory so as to minimize I/O, often trading programmability for performance. In this article we show how ...

    • openAccess   Algorithm 1022: Efficient Algorithms for Computing a Rank-Revealing UTV Factorization on Parallel Computing Architectures 

      Heavner, Nathan; Igual, Francisco D.; Quintana-Ortí, Gregorio; MARTINSSON, GUNNAR Association for Computing Machinery (ACM) (2022-06)
      Randomized singular value decomposition (RSVD) is by now a well-established technique for efficiently computing an approximate singular value decomposition of a matrix. Building on the ideas that underpin RSVD, the recently ...

    • openAccess   Algorithm 1033: Parallel Implementations for Computing the Minimum Distance of a Random Linear Code on Distributed-memory Architectures 

      Quintana-Ortí, Gregorio; Hernando, Fernando; Igual, Francisco D. Association for Computing Machinery (ACM) (2023-03)
      The minimum distance of a linear code is a key concept in information theory. Therefore, the time required by its computation is very important to many problems in this area. In this article, we introduce a family of ...

    • openAccess   An Algorithm-by-Blocks for SuperMatrix Band Cholesky Factorization 

      Quintana-Ortí, Gregorio; Quintana-Orti, Enrique S.; Remón Gómez, Alfredo; Van de Geijn, Robert A. Springer Verlag (2008)
      We pursue the scalable parallel implementation of the factor- ization of band matrices with medium to large bandwidth targeting SMP and multi-core architectures. Our approach decomposes the computation into a large ...

    • closedAccess   Blocked algorithms for the reduction to Hessenberg-triangular form revisited 

      Kagstrom, B.; Kressner, Daniel; Quintana-Orti, Enrique S.; Quintana-Ortí, Gregorio Springer (2008-09)
      We present two variants of Moler and Stewart’s algorithm for reducing a matrix pair to Hessenberg-triangular (HT) form with increased data locality in the access to the matrices. In one of these variants, a careful ...

    • openAccess   Computed tomography medical image reconstruction on affordable equipment by using Out-Of-Core technique 

      Chillarón, Mónica; Quintana-Ortí, Gregorio; Vidal, Vicente; Verdú, Gumersindo Elsevier (2020-09)
      Background and objective: As Computed Tomography scans are an essential medical test, many techniques have been proposed to reconstruct high-quality images using a smaller amount of radiation. One approach is to employ ...

    • openAccess   Contribución sobre el aprendizaje de la evaluación formativa: percepción del alumnado 

      Marqués-Andrés, Mercedes; Badía, José; Quintana-Ortí, Gregorio AENUI (Asociación de Enseñantes Universitarios de la Informática) (2020-07)
      En este trabajo se analiza la contribución sobre el aprendizaje de dos tipos de evaluación formativa según la percepción de los estudiantes de una asignatura de Bases de datos. Los dos tipos son el uso de cuestionarios ...

    • openAccess   Estimation of the neuromuscular fatigue threshold from an incremental cycling test using 1-minute exercise periods 

      Latasa, Iban; Cordova, Alfredo; Villa, Gerardo; Quintana-Ortí, Gregorio; Rodriguez-Falces, Javier Minerva Medica (2017-01)
      The objectives of this study were: 1) to evaluate the method used for estimating the neuromuscular fatigue threshold from surface electromyographic amplitude (the PWCFT test) during a single incremental cycling workout ...

    • openAccess   Evaluation of the Electromyography Test for the Analysis of the Aerobic-Anaerobic Transition in Elite Cyclists during Incremental Exercise 

      Latasa, Iban; Cordova, Alfredo; Quintana-Ortí, Gregorio; Lavilla-Oiz, Ana; Navallas, Javier; Rodriguez-Falces, Javier MDPI (2019-02-11)
      (1) Background: The aim of this study was to investigate the validity and reliability of surface electromyography (EMG) for automatic detection of the aerobic and anaerobic thresholds during an incremental continuous cycling ...

    • closedAccess   Exploiting the capabilities of modern GPUs for dense matrix computations 

      Barrachina Mir, Sergio; Castillo Catalán, María Isabel; Igual, Francisco D.; Mayo, Rafael; Quintana-Orti, Enrique S.; Quintana-Ortí, Gregorio John Wiley & Sons (2009)
      We present several algorithms to compute the solution of a linear system of equations on a graphics processor (GPU), as well as general techniques to improve their performance, such as padding and hybrid GPU-CPU computation. ...

    • closedAccess   Families of Algorithms for Reducing a Matrix to Condensed Form 

      Van Zee, Field G.; Van de Geijn, Robert A.; Quintana-Ortí, Gregorio; Elizondo, G. Joseph ACM (2012-11)
      In a recent paper it was shown how memory traffic can be diminished by reformulating the classic algorithm for reducing a matrix to bidiagonal form, a preprocess when computing the singular values of a dense matrix. The ...

    • openAccess   Fast Algorithms for the Computation of the Minimum Distance of a Random Linear Code 

      Hernando, Fernando; Igual, Francisco D.; Quintana-Ortí, Gregorio Association for Computing Machinery (ACM) (2019-06)
      The minimum distance of an error-correcting code is an important concept in information theory. Hence, computing the minimum distance of a code with a minimum computational cost is crucial to many problems in this area. ...

    • closedAccess   Fine-grained bit-flip protection for relaxation methods 

      Anzt, Hartwig; Dongarra, Jack; Quintana-Ortí, Gregorio Elsevier (2019-09)
      Resilience is considered a challenging under-addressed issue that the high performance computing community (HPC) will have to face in order to produce reliable Exascale systems by the beginning of the next decade. As part ...

    • openAccess   High-performance reconstruction of CT medical images by using out-of-core methods in GPU 

      Quintana-Ortí, Gregorio; Chillarón, Mónica; Vidal, Vicente; Verdu, Gumersindo Elsevier (2022-03-02)
      Background and objective:Since Computed Tomography (CT) is one of the most widely used medical imaging tests, it is essential to work on methods that reduce the radiation the patient is exposed to. Although there are several ...

    • openAccess   Householder QR Factorization With Randomization for Column Pivoting (HQRRP) 

      MARTINSSON, GUNNAR; Quintana-Ortí, Gregorio; Heavner, Nathan; Van de Geijn, Robert A. Society for Industrial and Applied Mathematics (2017)
      A fundamental problem when adding column pivoting to the Householder QR fac- torization is that only about half of the computation can be cast in terms of high performing matrix- matrix multiplications, which greatly ...

    • openAccess   Level-3 BLAS on a GPU: Picking the Low Hanging Fruit 

      Quintana-Ortí, Gregorio; Van de Geijn, Robert A. Departament d' Enginyeria i Ciència dels Computadors, Universitat Jaume I (2009-04)
      The arrival of hardware accelerators has created a new gold rush to be the rst to deliver their promise of high performance for numerical applications. Since they are relatively hard to program, with limited language ...

    • openAccess   Out-of-Core Solution of Linear Systems on Graphic Processors 

      Castillo Catalán, María Isabel; Igual, Francisco D.; Mayo, Rafael; Rubio, Rafael; Quintana-Ortí, Gregorio; Quintana-Orti, Enrique S.; Van de Geijn, Robert A. Departament d' Enginyeria i Ciència dels Computadors, Universitat Jaume I (2008-05)
      We combine two high-level application programming interfaces to solve large-scale linear systems with the data stored on disk using current graphics processors. The result is a simple yet powerful tool that enables a ...

    • openAccess   Parallelizing dense and banded linear algebra libraries using SMPSs 

      Badía Sala, Rosa María; Herrero, Josep R.; Labarta Mancho, Jesús; Pérez, Josep M.; Quintana-Orti, Enrique S.; Quintana-Ortí, Gregorio John Wiley (2009-12-25)
      The promise of future many-core processors, with hundreds of threads running concurrently, has led the developers of linear algebra libraries to rethink their design in order to extract more parallelism, further exploit ...

    • openAccess   Programming matrix algorithms-by-blocks for thread-level parallelism 

      Quintana-Ortí, Gregorio; Quintana-Orti, Enrique S.; Van de Geijn, Robert A.; Van Zee, Field G.; Chan, Ernie Association for Computing Machinery (2009-07)
      With the emergence of thread-level parallelism as the primary means for continued improvement of performance, the programmability issue has reemerged as an obstacle to the use of architectural advances. We argue that ...

    • openAccess   randUTV: A Blocked Randomized Algorithm for Computing a Rank-Revealing UTV Factorization 

      MARTINSSON, GUNNAR; Quintana-Ortí, Gregorio; Heavner, Nathan Association for Computing Machinery (2019-03)
      A randomized algorithm for computing a so-called UTV factorization efficiently is presented. Given a matrix , the algorithm “randUTV” computes a factorization , where and have orthonormal columns, and is triangular ...