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-/ .* Improved |
last updated: 2000-06-30 |
The monad -/ . * (determinant) on square matrices
is now implemented by Gaussian elimination with full pivoting.
(Previously, it used the general code for u . v
that worked for all verbs.)
The result is improved efficiency in time and space,
as the following comparisons illustrate:
ts=: 6!:2 , 7!:2@] x=: 0.01 * _5e4+?(n,n)$1e5 ts '-/ .* x'
n | J 4.05 | J 4.04 |
1 | 0.000155048 6720 | 0.000150857 6784 |
2 | 0.000163429 6912 | 0.000163429 6976 |
3 | 0.000150857 6720 | 0.000236343 9024 |
4 | 0.000153371 6848 | 0.000542248 16384 |
5 | 0.000155048 6848 | 0.00213714 25472 |
6 | 0.000190248 7104 | 0.0120828 43328 |
7 | 0.000165943 7104 | 0.0837802 80448 |
8 | 0.000175162 7616 | 0.66968 151936 |
9 | 0.000183543 7616 | 6.08026 239872 |
10 | 0.000196114 7616 | 60.9625 410304 |