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7.5. NUMERICAL EXPERIMENTS WITH JDCOMM SOFTWARE 127<br />

Figure 7.10: Sparsity structure of the matrices A p1 and A xi , i =1,...,4<br />

Table 7.17: Comparison between performance of JD and JDCOMM using various search<br />

space dimensions<br />

Value Value Time (s)<br />

mindim maxdim A p1 A x1 A x2 A x3 A x4<br />

5 30 11.6<br />

10 15 10.0<br />

10 25 15.4<br />

10 50 10.7 6.1<br />

10 75 6.8 41.5<br />

10 100 139.9 10.1 7.7 20.8 20.7<br />

method on the matrix A p1 computes the requested eigenvalue only in the case when<br />

the maximum search space dimension maxdim is 100, whereas the JDCOMM method<br />

using the matrix A x2 works in all cases with a superior performance. Note also that<br />

the increase of maxdim from 25 <strong>to</strong> 50 more than halves the computation time of the<br />

JDCOMM method on the matrix A x2 . Moreover, this is the fastest computation shown<br />

in Table 7.17.<br />

In Table 7.18 we give the more detailed results (with respect <strong>to</strong> required matrixvec<strong>to</strong>r<br />

products and flops) of the situation where all the eigenvalue methods succeed

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