Node:Configure files, Next:Output, Previous:Usage, Up:Glucas basics

Configuring and preferences.

In addition to the command line options we can use when invoking Glucas, there are some other options we can set in an ini file. By default this file's name is glucas.ini. If we want to use another than the default file we have to enter it as command line argument (See Usage.). The options must be in the form Option=value, one per line. No blank space is permitted. These are the supported Options:

Alternative_output_flag=[0/1/2]

If Verbose_Flag is active, then the output is written to a file pointed by File_output when Alternative_Output_Flag is set to 1. If zero, the output is stdout. If two, the output is send to both File_output and stdout.

Check_iteration=value

Set the number of iterations to do if Only_check_flag is enabled. It is useful in test/timings tasks.

File_output=my_output_file

When this line is included and Verbose_flag is active, then the verbose output is written to this file. If both Verbose_flag and Alternative_output_flag are active and no output file is given, the default is glucas.out file. Here only the name of the file is entered. The directory path must be added with -W option on the command line whenever this file is not in the current working directory.

Iteration_output=value

Set the rate of information when Verbose_flag is enabled. Iteration_output=n outputs information every n iterations. The default value is 10000.

Last_error_flag=[0/1]

If enabled (=1) and Verbose_flag is enabled, then the output includes the last computed roundoff error. The default is 0.

Only_check_flag=[0/1]

If enabled (=1), Glucas performs only a partial Lucas-Lehmer test. The number of iterations to do is controlled by Check_iteration. This option is useful for debugging and timing purposes. The default is 0.

QA_interim_file=n

To make QA tasks easy, Glucas will save an interim file every n iterations with this line. The format of the filename is sMMMMM_NNNN, where MMMMM is the exponent and NNNN the iteration saved. As example s9791209_00100000 would be the interim file for M(9791209) with the residue at iteration 100000. On the verbose output file, and on the results file, an output with the less significant bits of residue RES64 will be printed.

Roundoff_check=[0/1]

When it is active (=1), then the roundoff error check is activated for every iteration. When it is set to zero, then roundoff checking is completely disabled. Be careful with this option, a critical roundoff error might not be detected. Without this line Glucas will make a roundoff check for every iteration during the first 131032 iterations and every 64 iterations after that. If Glucas was compiled with the Y_SECURE flag, the roundoff check will be made for every iteration regardless of this setting.

Save_iterations=n

By default, Glucas writes a save file every 4096 iterations. The purpose of this file is to preserve the work already done. This file will be used as starting point when Glucas restarts after terminating or during the initial accuracy adjustment phase. If the verbose_flag is enabled, then the less significant bits of the residue (RES64) will be printed.

Time_flag=[0/1]

If enabled, Glucas prints the real time wasted from last output. If the system has the user time available it also prints it.

NOTE: From version 2.7, Glucas writes a random 32-bit integer as Identifier machine whether the ini file still has not one. The line appended is in the form

Computer_ID=n

and you should not modify this line. The g file also has this identifier of the machine which made the work. If the Computer_ID from ini and g files don't match, Glucas will take this as a change in the Hardware/Software context and will enable the roundoff error checking as in the first iterations of a Lucas-Lehmer test. This feature was added because the default format for save and interim files uses the interchangeable format, and therefore can be used by most platforms. It is thought as a method to detect if the save file used is from another machine.

Examples

Here are two examples of ini files.

The first example only runs a partial Lucas-Lehmer test.

Verbose_flag=1
Alternative_output_flag=1
File_output=my_file
Last_error_flag=1
Time_flag=1
Iteration_output=100
Only_check_flag=1
Check_iteration=1000

With this ini file. Glucas will write information to the file my_file every 100 iterations. The Lucas-Lehmer test will be terminated at iteration 1000. The output will include timings and roundoff errors. By default, the queue file will be glucas.que, unless we use another filename on the command line.

The second example is for a long and complete QA Lucas-Lehmer test.

Save_iterations=5000
QA_save_file=1000000
Verbose_flag=1
Alternative_output_flag=1
File_output=my_file
Last_error_flag=1
Time_flag=1
Iteration_output=10000
Only_check_flag=0

Here Glucas will write verbose information to the file my_file every 10000 iterations. It will write a save file every 5000 iterations and the residue RES64 will be printed. Every 1000000 iterations an interim file will be saved, and the RES64 will be printed in both my_file and results file.