Cleanup: simplify standard well equations

[michal-toth]

I just stumbled upon this while studying cprw solver. The code can be simplified in two ways:

1. The vector rhs has exactly one nonzero element equal to 1. The for loop accumulating elements multiplied by rhs can be thus simplified to an assignment.
2. The transposed inv_diag_block matrix does not have to be constructed. We access its elements, so swapping indices suffices.

[michal-toth]

jenkins build this please

[blattms]

benchmark please

[ytelses]

Benchmark result overview:

Test	Configuration	Relative
opm-git	OPM Benchmark: drogon - Threads: 1	1.001
opm-git	OPM Benchmark: drogon - Threads: 8	1.053
opm-git	OPM Benchmark: punqs3 - Threads: 1	0.998
opm-git	OPM Benchmark: punqs3 - Threads: 8	0.991
opm-git	OPM Benchmark: smeaheia - Threads: 1	1.04
opm-git	OPM Benchmark: smeaheia - Threads: 8	1.121
opm-git	OPM Benchmark: spe10_model_1 - Threads: 1	1.004
opm-git	OPM Benchmark: spe10_model_1 - Threads: 8	0.984
opm-git	OPM Benchmark: flow_mpi_extra - Threads: 1	1.004
opm-git	OPM Benchmark: flow_mpi_extra - Threads: 8	1.173
opm-git	OPM Benchmark: flow_mpi_norne - Threads: 1	1.001
opm-git	OPM Benchmark: flow_mpi_norne - Threads: 8	1.085
opm-git	OPM Benchmark: flow_mpi_norne_4c_msw - Threads: 1 - FOPT (Total Oil Production At End Of Run)	1
opm-git	OPM Benchmark: flow_mpi_norne_4c_msw - Threads: 8 - FOPT (Total Oil Production At End Of Run)	1

• Speed-up = Total time master / Total time pull request. Above 1.0 is an improvement. *

View result details @ https://www.ytelses.com/opm/?page=result&id=2712

[atgeirr]

Code looks correct to me.

However, I think it is not executed at all in the normal case, since the line

prm.put("preconditioner.use_well_weights", "false"s);

in setupPropertyTree.cpp means we use the other branch, unless you pass a custom JSON definition for the linear solver.

Therefore it would be prudent to do some testing with a custom definition setting this parameter to true, before merging.

[blattms]

However, I think it is not executed at all in the normal case,

Whether this is called is subject to the add_well property in the json-tree of the CPR preconditioner (see PressureBhpTransferPolicy.hpp#L203) and that seems to be true for our default, see setupPropertyTree.cpp#L144.

[blattms]

I take back my statement above, That is the condition that the function is called, but here is another if around this particular statement, indeed.