[JIRA] Updated: (JSR_275-35) Consider adding a UnitConverter.derivative(double) method

["keilw (JIRA)" <jira-no-reply@kenai.com>]

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http://kenai.com/jira/browse/JSR_275-35?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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keilw updated JSR_275-35:
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> Consider adding a UnitConverter.derivative(double) method
> ---------------------------------------------------------
>
>                 Key: JSR_275-35
>                 URL: http://kenai.com/jira/browse/JSR_275-35
>             Project: jsr-275
>          Issue Type: Improvement
>          Components: Spec
>    Affects Versions: 0.9.1
>            Reporter: Martin Desruisseaux
>            Priority: Minor
>   Original Estimate: 0 minutes
>  Remaining Estimate: 0 minutes
>
> Older version of the unit library (especially JSR-108) had the following 
> method:
> * {{double UnitConverter.derivative(double x)}}
> If we consider {{UnitConverter}} as a function of the kind _y=f\(x)_, then 
> the above method returns the derivative of that function at the given 
> value, i.e. _y'=f'\(x)_.
> I think that this value is well defined for every {{UnitConverter}} 
> currently available in the RI, and I don't foresee at this time a use case 
> where it could not be. For the vast majority of converters, it is a 
> constant (the scale factor) for all values of _x_. For a few converters 
> like the one for decibel, this is a simple logarithmic function. For a few 
> converters having discontinuities (like converters for sexagesimal angles), 
> the value may be {{Double.POSITIVE_INFINITY}} or 
> {{Double.NEGATIVE_INFINITY}} in a few locations, depending on the 
> discontinuity.
> This function would be useful for calculations requirying the derivative of 
> a function, for example finding the minimum or maximum of a function using 
> the Newton method where the function involves unit conversions. Other 
> standards like OGC 01-009 (_Coordinate Transformation Services_) provides 
> similar derivative function. For the Geotoolkit.org library, it is required 
> for filling the coefficients of the {{AffineTransform}} used for some 
> geographic coordinate conversions.

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