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docs: clarification and cleanup applied to "The Affine Space" chapter

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Mateusz Pusz
2023-08-03 13:17:51 +02:00
parent b8002d1940
commit bc2a3572ea
1 changed files with 16 additions and 6 deletions
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docs/users_guide/framework_basics/the_affine_space.md
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@@ -192,12 +192,22 @@ For this purpose, we can either use:
static_assert(qp.relative() == 5406 * m); static_assert(qp.relative() == 5406 * m);
``` ```
!!! note
It is allowed to only covert between various origins defined in terms of the same
`absolute_point_origin`. Even if it is possible to express the same _point_ as a _vector_
from another `absolute_point_origin`, the **mp-units** library will not allow it, and
a custom user-defined conversion function will be needed to provide such a functionality.
Said otherwise, in the **mp-units** library, there is no way to spell how two distinct
`absolute_point_origin` types relate to each other.
### _Point_ arithmetics ### _Point_ arithmetics
Let's assume we are going to attend the CppCon conference that is hosted in Aurora, CO, and we Let's assume we will attend the CppCon conference hosted in Aurora, CO, and we want to estimate
want to estimate the distance we are going to travel. We have to take a taxi to a local airport, fly to the distance we will travel. We have to take a taxi to a local airport, fly to DEN airport with
DEN airport with a stopover in FRA, and in the end, get a taxi to the Gaylord Rockies Resort & Convention a stopover in FRA, and in the end, get a cab to the Gaylord Rockies Resort & Convention Center:
Center:
```cpp ```cpp
constexpr struct home_location : absolute_point_origin<isq::distance> {} home_location; constexpr struct home_location : absolute_point_origin<isq::distance> {} home_location;
@@ -258,8 +268,8 @@ using Celsius_point = quantity_point<isq::thermodynamic_temperature[deg_C], ice_
!!! note !!! note
Notice that while stacking point origins we can use not only different representation types but Notice that while stacking point origins, we can use not only different representation types
also different units for an origin and a _point_. but also different units for an origin and a _point_.
With the above, for example, if we want to implement a room temperature controller, we can type: With the above, for example, if we want to implement a room temperature controller, we can type: