From b9aa48e98053e17530ed8fa4bae9a81b50a9fe67 Mon Sep 17 00:00:00 2001 From: Chip Hogg Date: Sun, 15 Oct 2023 08:46:40 -0400 Subject: [PATCH] Address comments from #44 --- ...for_a_physical_quantities_and_units_library.md | 2 +- src/2982R0_std_quantity_as_a_numeric_type.md | 15 ++++++++------- 2 files changed, 9 insertions(+), 8 deletions(-) diff --git a/src/2980R0_a_motivation_scope_and_plan_for_a_physical_quantities_and_units_library.md b/src/2980R0_a_motivation_scope_and_plan_for_a_physical_quantities_and_units_library.md index ee2c333..d9da9f8 100644 --- a/src/2980R0_a_motivation_scope_and_plan_for_a_physical_quantities_and_units_library.md +++ b/src/2980R0_a_motivation_scope_and_plan_for_a_physical_quantities_and_units_library.md @@ -11,7 +11,7 @@ author: email: - name: Johel Ernesto Guerrero Peña email: - - name: Charles Hogg + - name: Chip Hogg email: - name: Nicolas Holthaus email: diff --git a/src/2982R0_std_quantity_as_a_numeric_type.md b/src/2982R0_std_quantity_as_a_numeric_type.md index 926bf65..1423282 100644 --- a/src/2982R0_std_quantity_as_a_numeric_type.md +++ b/src/2982R0_std_quantity_as_a_numeric_type.md @@ -1002,10 +1002,10 @@ number. For example, the ratio between one foot and one inch is 12. ### Unit magnitudes In principle, this scaling factor can be any positive real number. In mp-units and Au, we have used the term -"magnitude" to refer to this scaling factor. (This should not be confused with the logarithmic "magnitude" -unit commonly used in astronomy.) +"magnitude" to refer to this scaling factor. (This should not be confused with other uses of the term, such +as the logarithmic "magnitude" unit commonly used in astronomy.) -In the library implementation, each unit is associated with a magnitude. However, for most units the +In the library implementation, each unit is associated with a magnitude. However, for most units, the magnitude is a fully encapsulated implementation detail, not a user-facing value. This is because the notion of "the" magnitude of a unit is not generally meaningful: it has no physically @@ -1016,10 +1016,11 @@ assign any magnitude $m_s$ to the second, because it's an independent dimension choice, it fixes the magnitude for derived units, and we must assign, say, $(5280 m_f) / (3600 m_s)$ to the _mile per hour_. -The one exception to the arbitrariness of magnitudes is _dimensionless_ units. Because their dimension is -null, quantities of these units can be meaningfully compared to their squares and other powers. For example, -the magnitude of _percent_ is $1 / 100$, and the magnitude of _squared percent_ (or _pertenk_, "per-10-k") is -$1 / 10000$. We cannot choose another value for the magnitude without producing observably incorrect results. +The one exception to the arbitrariness of magnitudes is _dimensionless_ units. Because their dimension is the +identity, quantities of these units can be meaningfully compared to their squares and other powers. For +example, the magnitude of _percent_ is $1 / 100$, and the magnitude of _squared percent_ (or _pertenk_, +"per-10-k") is $1 / 10000$. We cannot choose another value for the magnitude without producing observably +incorrect results. ### Requirements and Representation