# THRGIBBS1F90

## Options

### Save intermediate results for "cold start"

  OPTION save_halfway_samples n

This option can help the 'cold start' (to continue the sampling when the program accidentally stops before completing the run). An integer value n is needed. In every n rounds, the program saves intermediate samples to 2 files (last_solutions and binary_final_solutions). The program can restart the sampling form the last round where the intermediate files were saved. The program also writes a log file save_halfway_samples.txt with useful information for the next run.

To restart, add OPTION cont 1 to your parameter file and run thrgibbs1f90 again. Input 3 numbers (samples, burn-in, and interval) according to save_halfway_samples.txt. Thrgibbs1f90 can take care of all restarting process by itself, so no other tools are needed.

#### Tips

• Small n will make the program slow because of frequent file writing. The n should be a multiple of the interval (the 3rd number you will input in the beginning of the program).
• If the program stops during burn-in, the restart will fail because gibbs_samples is not created. Recommendation is burn-in=0 (but it doesn't provide posterior mean and SD for solutions).
• The cold start may add tiny numerical errors to the samples. Samples from the cold start wouldn't be identical to samples from a non-stop analysis.
• If, unfortunately, the program is killed during its saving the intermediate samples, the cold start will fail. To avoid this, you can manually make a backup for gibbs_samples, fort.99, last_solutions, and binary_final_solutions at some point and write them back if needed.

#### Example

Put the following option in your parameter file.

  OPTION save_halfway_samples 100

Run thrgibbs1f90. You will see the following message on screen.

  '**** saving halfway samples in every         100  rounds (default=0)

In this case, we assume the number of total samples is 3000, the burn-in is 0, and the interval is 10.

   number of samples and length of burn-in
3000 0
Give n to store every n-th sample? (1 means store all samples)
10

Make sure the intermediate results are saved to files.

          100  rounds
G
2758.       1900.       2019.
1900.       1690.       1656.
2019.       1656.       1737.
G
225.5      -91.35      -9.998
-91.35       403.5       474.6
-9.998       474.6       702.2
R
1755.       868.7       817.0
868.7       2122.       1361.
817.0       1361.       1804.
* Last seeds =  1877469549   348652151
* Number of samples kept =         100
solutions stored in binary file: "last_solutions"
solutions stored in file: "binary_final_solutions"

Stop the program. In this case, program stops in the round 880.

           880  rounds
forrtl: error (69): process interrupted (SIGINT)
Image              PC                Routine            Line        Source
thrgibbs1f90       0000000000943031  Unknown               Unknown  Unknown
thrgibbs1f90       0000000000941787  Unknown               Unknown  Unknown

Make sure there are the following 5 files.

  binary_final_solutions  fort.99  gibbs_samples  last_solutions  save_halfway_samples.txt

Browse the file save_halfway_samples.txt. Only information in the 'suggestion' block is needed for the next run. The halfway samples were saved in the round 800 so you will start the sampling from the round 801 in the next run. Remaining 2200 rounds are needed to satisfy the initial goal (3000 rounds).

  Saved on 2017-03-10 10:53:22

State in the current run:
last round              =        800
sampled in this run     =        800
total number of samples =       3000
number of burn-in       =          0
interval                =         10

Suggestion for the input in next run:
total number of samples =       2200
number of burn-in       =          0
interval                =         10

When you restart the program, do not forget to put the following option
OPTION cont 1

Put the option OPTION cont 1 to your parameter file. It can invoke the 'cold start' module in thrgibbs1f90.

  OPTION cont 1

Run thrgibbs1f90 again. You will see the following message on screen.

  '*** continuous sampling selected *** previous # samples =           1

NOTE: Although the message may say the previous number of sample is 1, you can ignore it. The program recognizes it is the cold start mode and works correctly.

Input the three numbers that are shown in save_halfway_samples.txt.

   number of samples and length of burn-in
2200 0
Give n to store every n-th sample? (1 means store all samples)
10

The program will start from the round 801 as expected.

           801  rounds
G
828.0       601.3       610.8
601.3       996.3       877.4
610.8       877.4       822.8
G
2541.       1531.       1756.
1531.       1459.       1598.
1756.       1598.       1898.
R
1800.       833.0       813.3
833.0       2114.       1303.
813.3       1303.       1778.    

Just wait the analysis. You can interrupt the program again. The final results will be basically the same to ones from a non-stop analysis.