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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 |
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