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Mixed Precision in Uncertainty Quantification Methods
Název práce v češtině: Mixed Precision in Uncertainty Quantification Methods
Název v anglickém jazyce: Mixed Precision in Uncertainty Quantification Methods
Klíčová slova: Uncertainty quantification|Multilevel|Monte Carlo|Mixed precision|Iterative refinement
Klíčová slova anglicky: Uncertainty quantification|Multilevel|Monte Carlo|Mixed precision|Iterative refinement
Akademický rok vypsání: 2021/2022
Typ práce: diplomová práce
Jazyk práce: angličtina
Ústav: Katedra numerické matematiky (32-KNM)
Vedoucí / školitel: Erin Claire Carson, Ph.D.
Řešitel: skrytý - zadáno a potvrzeno stud. odd.
Datum přihlášení: 01.02.2022
Datum zadání: 01.02.2022
Datum potvrzení stud. oddělením: 14.02.2022
Datum a čas obhajoby: 09.06.2023 09:00
Datum odevzdání elektronické podoby:01.05.2023
Datum odevzdání tištěné podoby:09.05.2023
Datum proběhlé obhajoby: 09.06.2023
Oponenti: doc. RNDr. Iveta Hnětynková, Ph.D.
 
 
 
Konzultanti: Robert Scheichl
Zásady pro vypracování
This works involves studying the opportunities for the use of mixed precision within uncertainty quantification methods. After developing a background on mixed precision computation and methods in uncertainty quantification, a model problem (ODE or PDE) will be chosen for study. Numerical experiments will be performed, varying the precision used in different parts of the code to determine how this affects the output. The potential for theoretical explanation and/or generalization to other methods will be explored.
Seznam odborné literatury
Abdelfattah, A., Anzt, H., Boman, E. G., Carson, E., Cojean, T., Dongarra, J., et al. (2021). A survey of numerical linear algebra methods utilizing mixed-precision arithmetic. The International Journal of High Performance Computing Applications, 35(4), 344-369.

Higham, N. J. (2002). Accuracy and stability of numerical algorithms. Society for industrial and applied mathematics.

Dodwell, T. J., Ketelsen, C., Scheichl, R., & Teckentrup, A. L. (2019). Multilevel markov chain monte carlo. Siam Review, 61(3), 509-545.

Sullivan, T. J. (2015). Introduction to uncertainty quantification (Vol. 63). Springer.

Ghanem, R., Higdon, D., & Owhadi, H. (Eds.). (2017). Handbook of uncertainty quantification (Vol. 6). New York: Springer.
Předběžná náplň práce
Mathematical models for real-world problems often have parameters that are impossible to fully or accurately determine. In order to access the reliability of model output, it is necessary to quantify the uncertainty in model outputs due to uncertainty in model inputs. This can be achieved through stochastic modeling involving sampling from a posterior distribution. As sampling from the posterior distribution is often intractable, one method is to use a Markov chain Monte Carlo (MCMC) approach. For large-scale applications, however, the high number of samples and accuracy requirements result in the MCMC approach being computationally expensive. A recent development is the idea of multilevel MCMC (MLMCMC), which uses samples at difference resolution levels to reduce the computational cost.

A natural idea is to determine whether we can use low precision in select parts of this computation (i.e., the samples on coarse grid resolutions) to further reduce the computational cost without affecting the output. This could be especially beneficial from a performance standpoint for scenarios where coarse sampling is still the dominant computational cost.
Předběžná náplň práce v anglickém jazyce
Mathematical models for real-world problems often have parameters that are impossible to fully or accurately determine. In order to access the reliability of model output, it is necessary to quantify the uncertainty in model outputs due to uncertainty in model inputs. This can be achieved through stochastic modeling involving sampling from a posterior distribution. As sampling from the posterior distribution is often intractable, one method is to use a Markov chain Monte Carlo (MCMC) approach. For large-scale applications, however, the high number of samples and accuracy requirements result in the MCMC approach being computationally expensive. A recent development is the idea of multilevel MCMC (MLMCMC), which uses samples at difference resolution levels to reduce the computational cost.

A natural idea is to determine whether we can use low precision in select parts of this computation (i.e., the samples on coarse grid resolutions) to further reduce the computational cost without affecting the output. This could be especially beneficial from a performance standpoint for scenarios where coarse sampling is still the dominant computational cost.
 
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