About AmgX Result Printing

Hi dear reader:

I am trying to use AmgX library to solve Ax=b: using block jacobi preconditioned FGMRES solver.

As indicated in the reference, I am using a config file to build the solver temporarily:

mpirun -n 2  ./amgx_mpi_capi -mode dDDI -m ./matrix.mtx -c ../configs/config_file

And in the config file I did as in the reference book said or somewhat it said:

config_version=2
print_grid_stats=1
store_res_history=1
solver(fgmres)=FGMRES
print_solve_stats=1
fgmres:tolerance=0.01
fgmres:max_iters=40
fgmres:gmres_n_restart=10
fgmres:preconditioner(bjacobi)=BLOCK_JACOBI
bjacobi:relaxation_factor=0.5
obtain_timings=1
max_iters=100
monitor_residual=1

Then I got this
Process 1 selecting device 1
Process 0 selecting device 0
License acquired, proceeding
License acquired, proceeding
AMGX version 1.2.0-build108
Built on Dec 22 2014, 10:33:38
Compiled with CUDA Runtime 6.5, using CUDA driver 7.0
Cannot read file as JSON object, trying as AMGX config
Cannot read file as JSON object, trying as AMGX config
Converting config string to current config version
Parsing configuration string: exception_handling=1 ;
Reading matrix dimensions in file: ./matrix.mtx
Reading data…
RHS vector was not found. Using RHS b=[1,…,1]^T
Solution vector was not found. Setting initial solution to x=[0,…,0]^T
Finished reading

And then nothing, I cannot see any result. Can somebody help?

Also, how do I set the block size and other things? I cannot find much information about smoother used as preconditioner, the general parameters, FGMRES parameters and pbjacobi parameters are not fully shown in any materials either, can somebody post them or…maybe I missed them somewhere?

.

This is our number 1 problem: folks are having trouble understanding the configuration format and it’s rules.

To see the output, you should associate the print_solve_stats with the FGMRES outer solver.

fgmres:print_solve_stats=1

Just modifying that line should help, but you will also need to store the residual history for that solver, so
fgmres:monitor_residual=1
fgmres:store_res_history=1
fgmres:obtain_timings=1

should also be set.

Thank you jeaton,
I now are able to print the result