[petsc-dev] New ILU, associativity changes
Jed Brown
jed at 59A2.org
Wed Feb 24 02:55:45 CST 2010
I notice low-bit differences between the new ILU and versions from last
month. From one of my tests:
-Algebraic residual |x|_1 9.35e-16 |x|_2 2.59e-16 |x|_inf 1.67e-16
+Algebraic residual |x|_1 1.09e-15 |x|_2 3.00e-16 |x|_inf 1.67e-16
-Algebraic residual |x|_1 6.18e-12 |x|_2 2.59e-13 |x|_inf 4.08e-14
+Algebraic residual |x|_1 6.19e-12 |x|_2 2.59e-13 |x|_inf 4.08e-14
-Algebraic residual |x|_1 4.85e-12 |x|_2 1.95e-13 |x|_inf 4.73e-14
+Algebraic residual |x|_1 4.84e-12 |x|_2 1.95e-13 |x|_inf 4.73e-14
-Algebraic residual |x|_1 3.36e-13 |x|_2 1.56e-14 |x|_inf 3.06e-15
+Algebraic residual |x|_1 3.32e-13 |x|_2 1.54e-14 |x|_inf 3.05e-15
I'm guessing this comes from traversing rows in the other order during
backsolve. This is no problem at all since both are equally valid, I
just wanted to note that some rounding effects are visible.
Jed
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