On Thursday, 13 May 2021 at 03:03:37 UTC, Tim wrote:
```
unittest{
auto p = rotate2D([0.0, 10.0], PI_2);
assert(p == [-10.0, 0.0]);
}
```
I suggest
```
unittest
{
auto p = rotate2D([0.0, 10.0], PI_2);
assert(isClose(p[0], -10.0));
assert(isClose(p[1], 0.0, 0.0, 1e-6));
}
```
In the second test, the value is compared against zero, which is
somewhat special - you need to specify an acceptable distance
from zero to get it right.
You could also improve your result by making the `phi` a `double`
value. In this case you can replace the `1e-6` above by `1e-15`
which is much closer to zero.
