MIME-Version: 1.0
From: Thom Brown <thom@linux.com>
Date: Thu, 23 Jun 2011 10:46:09 +0100
Message-ID: <BANLkTimct3DOjrcXqzV9cCWdzFVF_HFYLw@mail.gmail.com>
Subject: Functions example results incorrect
To: pgsql-docs <pgsql-docs@postgresql.org>
Content-Type: text/plain; charset=ISO-8859-1

I've been looking at some of the functions listed in the docs and
noticed some apparent discrepancies.

This page of the docs doesn't seem to match real output for exp or ln:
http://www.postgresql.org/docs/9.0/static/functions-math.html

It says that exp(1.0) yields 2.71828182845905.

Testing on 3 different systems shows an answer with two more
significant figures: 2.7182818284590452

The same for ln(2.0), which the example gives as 0.693147180559945,
but for me it's 0.6931471805599453.

And sqrt(2.0) has the example output of 1.4142135623731, but I get
1.414213562373095.

For log(100.0), the output is 2, which doesn't match the definition
since it claims the return type should be the same as the input, which
in this case it clearly isn't.  Trying this out returns
2.0000000000000000.

The log function for which the base is passed, and the type of which
should always be numeric shows an example output for log(2.0, 64.0) as
6.0000000000.  My output returns 6.0000000000000000, so 6 extra
digits.

The power function appears on 2 lines showing that it accepts double
precision or numeric.  The double precision example appears to be
wrong because it will be assumed the value is double precision unless
the value is explicitly cast.  In either case, the output wouldn't
have zero decimal places as shown in the example output.

Also, on the string functions page
(http://www.postgresql.org/docs/9.0/static/functions-string.html), the
output for the decode example shows an escape formatted output.  This
isn't the case by default in 9.0, so that should be changed, and maybe
a reference to a page explaining how the output depends on the
configuration of bytea_output.

The quote literal example of quote_literal('O\'Reilly') doesn't work
on my installation by default.  It assumes I'm using a client encoding
that allows backslash within a multibyte character and that I have
backslash_quote set to safe_encoding.

Can someone confirm whether these are valid complaints?

-- 
Thom Brown
Twitter: @darkixion
IRC (freenode): dark_ixion
Registered Linux user: #516935

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