Dataplot Vol 1 Vol 2

# SEED

Name:
SEED
Type:
Support Command
Purpose:
Specify the seed for random number generation.
Description:
Each distinct seed generates a different sequence of random numbers (the seed allows the random number generator to duplicate the same sequence of random numbers).

Dataplot supports several different random number generators. The desired generator can be set with the command

SET RANDOM NUMBER GENERATOR <generator>

where <generator> is one of the following:

FIBONACCI
LINEAR CONGRUENTIAL
MULTIPLICATIVE CONGRUENTIAL
GFSR
FUSHIMI
AS183
GENZ
LUXURY
FIBONACCI CONGRUENTIAL

The deault generator is the FIBONACCI CONGRUENTIAL generator (the default prior to 2018/05 was the FIBONACCI generator).

The seed value applies to the following generators

FIBONACCI
FIBONACCI CONGRUENTIAL
MULTIPLICATIVE CONGRUENTIAL
AS183

For the FIBONACCI and FIBONACCI CONGRUENTIAL generators, the minimum seed value should be 305 and the seed should be an odd number. Values of the seed less than 305 are equivalent to 305 and even values of the seed are equivalent to the nearest odd number.

For the other generators, if you want to obtain a different sequence of random numbers you can do something like the following

LET ISKIP = 50000
LET NRAND = 10000
LET YJUNK = UNIFORM RANDOM NUMBERS FOR I = 1 1 ISKIP
LET Y = UNIFORM RANDOM NUMBERS FOR I = 1 1 NRAND

This example will first generate 50,000 random numbers that will not be used. It then generates 10,000 random numbers that will be used. To obtain a different sequence of random numbers, modify the value of ISKIP.

Syntax:
SEED <iseed>
where <iseed> is an integer number or parameter that defines the seed.
Examples:
SEED 55671
SEED DEFAULT
Note:
To return the current value of the seed, enter

PROBE SEED
Default:
305 (Prior to 2019/03)
3005 (2019/03)
Synonyms:
None
Related Commands:
 RANDOM NUMBERS (LET) = Generate random numbers for various distributions. SET RANDOM NUMBER GENERATOR = Specify the random number generator to use.
Applications:
Random Number Generation
Implementation Date:
Pre-1987
Program:

SEED 4021
LET Y1 = NORMAL RANDOM NUMBERS FOR I = 1 1 100
SEED 34201
LET Y2 = NORMAL RANDOM NUMBERS FOR I = 1 1 100
SEED 19793
LET Y3 = NORMAL RANDOM NUMBERS FOR I = 1 1 100
SEED 46987
LET Y4 = NORMAL RANDOM NUMBERS FOR I = 1 1 100
LINE COLOR BLACK BLUE RED GREEN
MULTIPLE KERNEL DENSITY PLOT Y1 Y2 Y3 Y4

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Date created: 01/08/2020
Last updated: 01/08/2020