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From Sébastien Brisard <sebastien.bris...@m4x.org>
Subject Re: [Math] Formatting (Was: svn commit: r1379270 - /commons/proper/math/trunk/...)
Date Fri, 31 Aug 2012 13:52:10 GMT
Hi Gilles,

2012/8/31 Gilles Sadowski <gilles@harfang.homelinux.org>:
> Hello Sébastien.
>
>> Author: celestin
>> Date: Fri Aug 31 03:12:16 2012
>> New Revision: 1379270
>>
>> URL: http://svn.apache.org/viewvc?rev=1379270&view=rev
>> Log:
>> MATH-849: changed boundary case x = 8.0 in double Gamma.logGamma(double).
>>
>> Modified:
>>     commons/proper/math/trunk/src/main/java/org/apache/commons/math3/special/Gamma.java
>>
>> Modified: commons/proper/math/trunk/src/main/java/org/apache/commons/math3/special/Gamma.java
>> URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math3/special/Gamma.java?rev=1379270&r1=1379269&r2=1379270&view=diff
>> ==============================================================================
>> --- commons/proper/math/trunk/src/main/java/org/apache/commons/math3/special/Gamma.java
(original)
>> +++ commons/proper/math/trunk/src/main/java/org/apache/commons/math3/special/Gamma.java
Fri Aug 31 03:12:16 2012
>> @@ -222,9 +222,9 @@ public class Gamma {
>>       * Returns the value of log&nbsp;&Gamma;(x) for x&nbsp;&gt;&nbsp;0.
>>       * </p>
>>       * <p>
>> -     * For x &lt; 8, the implementation is based on the double precision
>> +     * For x &le; 8, the implementation is based on the double precision
>
> My personal taste would be to write this as
> ---
>  {@code x <= 8}
> ---
> [As I'm not an HTML parser,
>
I'm a bit disappointed by your poor parsing capabilities ;-)

> it always takes me a few moments to figure out a
> sequence such as "x &lt; 8", while it is easier to focus on the central part
> of "{@code x <= 8}".]
>
> So, if nobody disagrees, this could become a formatting rule. [The rationale
> (to be included in the document you proposed to create) would be that
> Javadoc comments should be as easy as possible to read in their source form,
> for the developer's sake.]
>
Yeah, and it gets worse when I had to find a work around for the
decimal point not being interpreted as the end of the first sentence:
I ended up with something like
Returns the value of 1 / &Gamma;(1 + x) - 1 for -0&#46;5 &le; x &le;
1&#46;5. In case you wondered, &#46; is simply '.'. This is uggly, I
agree.

I was thinking this very morning of something like "HTML tags are
allowed as long as reading the source file is still reasonably easy".
I'm quite happy with a more radical approach, like "HTML text
formatting tags should be avoided as much as possible. Paragraph
formatting (<p>, <li>, <pre>, ... is allowed)". Note that it has not
been applied consistently in CM yet : in some parts, formulae are
formatted with HTML tags, in other parts, it's pure {@code }. I
contributed to this mess :-(
As sebb mentions {@code } prevents *any* formatting, but this would
not really be an issue. If needed, we can use <pre></pre> tags and
nice text-based equations (again, tools like Maxima can help a lot),
even if it looks old fashioned.

I'll write something up in the JIRA ticket, so that everyone can review it.

Thanks for this suggestion,

Sébastien
>
> Best regards,
> Gilles
>
>>       * implementation in the <em>NSWC Library of Mathematics Subroutines</em>,
>> -     * {@code DGAMLN}. For x &ge; 8, the implementation is based on
>> +     * {@code DGAMLN}. For x &gt; 8, the implementation is based on
>>       * </p>
>>       * <ul>
>>       * <li><a href="http://mathworld.wolfram.com/GammaFunction.html">Gamma
>> @@ -249,7 +249,7 @@ public class Gamma {
>>              return logGamma1p(x) - FastMath.log(x);
>>          } else if (x <= 2.5) {
>>              return logGamma1p((x - 0.5) - 0.5);
>> -        } else if (x < 8.0) {
>> +        } else if (x <= 8.0) {
>>              final int n = (int) FastMath.floor(x - 1.5);
>>              double prod = 1.0;
>>              for (int i = 1; i <= n; i++) {
>>
>>
>
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