mpusz/mp-units
1
0
Fork 1
mirror of https://github.com/mpusz/mp-units.git synced 2025-08-01 03:14:29 +02:00
Code Issues Packages Projects Releases Wiki Activity

docs: outdated affine space chapter updated

Browse Source
This commit is contained in:
Mateusz Pusz
2023-12-01 11:32:44 +01:00
parent b6b5832c56
commit 5121eca121
1 changed files with 8 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
docs/users_guide/framework_basics/the_affine_space.md
View File

@@ -110,11 +110,11 @@ quantity_point qp5{-42 * m, mean_sea_level};
```
The provided `quantity` representing an offset from the origin is stored inside the `quantity_point`
class template and can be obtained with a `quantity_from_origin()` member function:
class template and can be obtained with a `quantity_from(PointOrigin)` member function:
```cpp
constexpr quantity_point everest_base_camp_alt = mean_sea_level + isq::altitude(5364 * m);
static_assert(everest_base_camp_alt.quantity_from_origin() == 5364 * m);
static_assert(everest_base_camp_alt.quantity_from(mean_sea_level) == 5364 * m);
```
@@ -137,17 +137,12 @@ The above can be used as an origin for subsequent _points_:
```cpp
constexpr quantity_point first_climb_alt = everest_base_camp + isq::altitude(std::uint8_t{42} * m);
static_assert(first_climb_alt.quantity_from_origin() == 42 * m);
static_assert(first_climb_alt.quantity_from(everest_base_camp) == 42 * m);
static_assert(first_climb_alt.quantity_from(mean_sea_level) == 5406 * m);
```
As we can see above, the `quantity_from_origin()` member function returns a relative distance from
the current point origin. In case we would like to know the absolute altitude that we reached on this climb,
we can subtract the absolute point origin from the current _point_:
```cpp
static_assert(first_climb_alt - mean_sea_level == 5406 * m);
static_assert(first_climb_alt - first_climb_alt.absolute_point_origin == 5406 * m);
```
As we can see above, the `quantity_from()` member function returns a relative distance from the
provided point origin.
### Converting between different representations of the same _point_
@@ -162,14 +157,14 @@ For this purpose, we can either use:
```cpp
constexpr quantity_point<isq::altitude[m], mean_sea_level, int> qp = first_climb_alt;
static_assert(qp.quantity_from_origin() == 5406 * m);
static_assert(qp.quantity_ref_from(qp.point_origin) == 5406 * m);
```
- a dedicated conversion interface:
```cpp
constexpr quantity_point qp = first_climb_alt.point_for(mean_sea_level);
static_assert(qp.quantity_from_origin() == 5406 * m);
static_assert(qp.quantity_ref_from(qp.point_origin) == 5406 * m);
```
!!! note