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From "Martin Desruisseaux (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (SIS-429) Arithmetic operation on quantities on values converted to system units
Date Sun, 29 Jul 2018 15:59:00 GMT

     [ https://issues.apache.org/jira/browse/SIS-429?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Martin Desruisseaux updated SIS-429:
------------------------------------
    Description: 
The result of arithmetic operations on quantities shall be as if all values were converted
to system quantities before the operations is performed. For most units, it make no difference.
But for temperature in Celsius, it as more complex consequences (1°C + 2°C = 276.15 °C).
While the above seems counter-intuitive, it is essential for preserving arithmetic laws like
associativity and commutativity.

The more intuitive result (1°C + 2°C = 3°C) requires that one of the operands is treated
as a _temperature increment_ instead than a _temperature measurement_. Such distinction is
out of scope of the issue, since it would require a change in Unit API.

  was:
The result of arithmetic operations on quantities shall be as if all values were converted
to system quantities before the operations is performed. For most units, it make no difference.
But for temperature in Celsius, it as more complex consequences (1°C + 2°C = 276.15 °C).
While the above seems counter-intuitive, it is essential for preserving arithmetic laws like
associativity and commutativity.

The more intuitive result (1°C + 2°C = 3°C) requires than one of the operand is treated
as a _temperature increment_ instead than a _temperature measurement_. Such distinction is
out of scope of the issue, since it would require a change in Unit API.


> Arithmetic operation on quantities on values converted to system units
> ----------------------------------------------------------------------
>
>                 Key: SIS-429
>                 URL: https://issues.apache.org/jira/browse/SIS-429
>             Project: Spatial Information Systems
>          Issue Type: Improvement
>            Reporter: Martin Desruisseaux
>            Assignee: Martin Desruisseaux
>            Priority: Major
>             Fix For: 1.0
>
>
> The result of arithmetic operations on quantities shall be as if all values were converted
to system quantities before the operations is performed. For most units, it make no difference.
But for temperature in Celsius, it as more complex consequences (1°C + 2°C = 276.15 °C).
While the above seems counter-intuitive, it is essential for preserving arithmetic laws like
associativity and commutativity.
> The more intuitive result (1°C + 2°C = 3°C) requires that one of the operands is treated
as a _temperature increment_ instead than a _temperature measurement_. Such distinction is
out of scope of the issue, since it would require a change in Unit API.



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