UpdateSeed (RandomNumberGenerator subroutine): Difference between revisions
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<tr><th>randomNumberGenerator</th> | <tr><th>randomNumberGenerator</th> | ||
<td>A <var>RandomNumberGenerator</var> object variable. </td></tr> | <td>A <var>RandomNumberGenerator</var> object variable. </td></tr> | ||
<tr><th>Seed</th> | <tr><th><var>Seed</var></th> | ||
<td>An optional, name required, argument that lets you specify a "seed" for the random number generator. If you provide no seed, the method generates a new, "random," starting value for the random number generator. | <td>An optional, name required, argument that lets you specify a "seed" for the random number generator. If you provide no seed, the method generates a new, "random," starting value for the random number generator. | ||
<var>Seed</var> is a string. </td></tr> | <var>Seed</var> is a string. </td></tr> | ||
<tr><th>Salt</th> | <tr><th><var>Salt</var></th> | ||
<td>An optional, name required, argument that lets you specify a "salt" for the random number generator. A salt is additional data to be used (along with the explicit or default seed) to improve the randomness of the random generator's initial value. | <td>An optional, name required, argument that lets you specify a "salt" for the random number generator. A salt is additional data to be used (along with the explicit or default seed) to improve the randomness of the random generator's initial value. | ||
Revision as of 22:32, 12 April 2011
Reset random sequence with new salt and seed (RandomNumberGenerator class)
This method sets a random number object to the number
that would be created by the New constructor
with the given Seed and Salt specifications.
Syntax
randomNumberGenerator:UpdateSeed[( [Seed= string], [Salt= string])]
Syntax terms
| randomNumberGenerator | A RandomNumberGenerator object variable. |
|---|---|
| Seed | An optional, name required, argument that lets you specify a "seed" for the random number generator. If you provide no seed, the method generates a new, "random," starting value for the random number generator. Seed is a string. |
| Salt | An optional, name required, argument that lets you specify a "salt" for the random number generator. A salt is additional data to be used (along with the explicit or default seed) to improve the randomness of the random generator's initial value. salt is a string. |
Examples
In the following request, calling updateSeed enables the production of a second series of three values of %rand that matches the initial series of three values of %rand:
begin %i is float %rand is object RandomNumberGenerator %rand = new(seed='help') for %i from 1 to 3 printtext {~} = {%rand:value} end for %rand:updateSeed(seed='help') for %i from 1 to 3 printtext {~} = {%rand:value} end for end
The result is:
%rand:value = 816969049 %rand:value = -148817379 %rand:value = 895846046 %rand:value = 816969049 %rand:value = -148817379 %rand:value = 895846046
If instead the random number is created with a salt, as in the following fragment, an updateSeed call using the salt produces a unique series of three values (salted numbers are not reproducible):
... %rand = new(salt='iou') for %i from 1 to 3 printtext {~} = {%rand:value} end for %rand:updateSeed(salt='iou') for %i from 1 to 3 printtext {~} = {%rand:value} end for
A sample result is:
%rand:value = 320947512 %rand:value = 535019615 %rand:value = -526589924 %rand:value = 387949238 %rand:value = 413468100 %rand:value = -807607538