1 Introduction
Table 1. Decomposed times (in seconds) of the randUTV factorization of large matrices of dimension n×n on the ut and ucm platforms.
['[EMPTY]', 'ut', 'ucm']
To check the benefits of the overlapping of computation and I /O in the other platforms ucm when no orthornormal matrices are built and q=0 (the power iteration process). To build this table, each operation in the factorization (both computational and I/O) was recorded. As can be seen, in ut the performances are very encouraging because the I/ O time is much smaller than the computational time (about 18 %), thus making the application computation-bound. However, in ucm the results are different since the disk of ut is 5.4 times as fast as the disk of ucm. The slower disk of ucm makes that the overall computational time and the overall I/ O time are similar, the latter being slightly larger. On the other side, in ut the overlapping of computation and I /O is perfect since the real time is only 0.12 % larger than the computational time. In ucm the overlapping of computation and I/O is almost perfect since the real time is only 27 % larger than the computational time, and 13 % larger than the I/O time (in this case larger than the computational time).