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From: Thom Brown <[email protected]>
To: pgsql-docs <[email protected]>
Subject: Re: Functions example results incorrect
Date: Thu, 23 Jun 2011 11:41:26 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

On 23 June 2011 10:46, Thom Brown <[email protected]> wrote:
> 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?

The same non-default bytea output representations are also shown on
all examples on
http://www.postgresql.org/docs/9.0/static/functions-binarystring.html
where bytea is the output type.

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

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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