Mistyped periods for random number generators

ROOT
1

Hi,

In the description of CERN ROOT pseudo-random number generator facilities here:

http://root.cern.ch/download/doc/ROOTUsersGuideHTML/ch13s02.html

the “periods” of the generators are incorrect. The errors are obvious for a public familiar with random number generation, but could possibly confuse other people.

The text says that TRandom [quote]“has a very short period, 231,about 109”[/quote].

This is obviously way too short :smiley: ; in fact the period is 2 to the 31st power, not 231;
In Fortran style, that would be written as “231 about 109”, or with HTML tags:
231 about 109 (one billion)

The same error is made just below within the same page, when describing the periods for generators TRandom1, TRandom2, TRandom3.
Namely:
10171 --> 10171
1026 --> 1026
106000 -->10**6000 (where for Mersenne-Twister, 6000 comes from 19937*(log(2)/log(10))

Also the same error appears when describing the gRandom global variable here:
http://root.cern.ch/download/doc/ROOTUsersGuideHTML/ch02s06.html
where 10600 should be made 10**6000.

Finally, the same errors seem to appear in the PDF version of the users guide:
http://root.cern.ch/download/doc/ROOTUsersGuide.pdf

Thanks a lot for your help,
Jean-Paul

2

Thanks for reporting.
The exponents were not properly translated when we converted the word document to docbook.
The right tag is . We will fix that.

3

Fixed on the ROOT web site.
Let us know if you find more mistakes.