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 ; in fact the period is 2 to the 31st power, not 231;

In Fortran style, that would be written as “2**31 about 10**9”, or with HTML tags:

2^{31} about 10^{9} (one billion)

The same error is made just below within the same page, when describing the periods for generators TRandom1, TRandom2, TRandom3.

Namely:

10171 --> 10**171
1026 --> 10**26

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