[Bug libstdc++/32822] New: More Hash Document Errors

["chalathip at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

+++ This bug was initially created as a clone of Bug #32819 +++

from libstdc++-v3/docs/html/ext/pb_ds/hash_based_containers.html
In the Bug #32819, I report 2 errors. But I found one more bug.

Section : Hash Table Design - Hash Policies - Ranged-Hash Functions

Original text :
Now assume that s is the string representation of a of a long DNA sequence (and
so S = {'A', 'C', 'G', 'T'}). In this case, scanning the entire string might be
prohibitively expensive. A possible alternative might be to use only the first
k characters of the string, where
k^|S| ≥ m               ---------- (1)
...
requiring scanning over only 
k = log4( m )           ---------- (2)
characters.

My suggestion:
In my humble opinion, I think that the first equation should be changed to
|S|^k ≥ m
Otherwise, the second equation should be changed to
k=m^(1/4)

Anyway if the form of the second equation is changed from
k = xxx
to
k = integral_ceiling (xxx)
or something looks like
k= [xxx]             ,(but the brackets should have only their upper halves ),
it might be a little more accurate. 

Best regards,
Chalathip Thumkanon.


-- 
           Summary: More Hash Document Errors
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: chalathip at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32822