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