Feature Request Unity.Mathematics is incomplete. Here's what's missing (and few custom ones)

Feel free to share more missing functions from the package. I don't get why they wouldn't be included, as they are all pretty useful.
I'm planning to write some more as soon as I need them.

I tested some of them but there might be some edge cases and issues with some of these functions.

Vector3.ProjectOnPlane
Quaternion.FromToRotation
Quaternion.Angle

Code (CSharp):

1. const float epsilon = 1E-6f;
2. // Same as from-to rotation, but with an in-between vector in case the two vectors are opposites.
3. [MethodImpl(MethodImplOptions.AggressiveInlining)]
4. public static quaternion FromToRotationSafe (float3 dir1, float3 dir2, float3 middlePointIfOpposite)
5. {
6.     float r = 1f + math.dot(dir1, dir2);
7.  
8.     if (r < epsilon)
9.     {
10.         return math.mul(FromToRotation(dir1, middlePointIfOpposite), FromToRotation(middlePointIfOpposite, dir2));
11.     }
12.     else
13.     {
14.         return FromToRotation(dir1, dir2);
15.     }
16. }
17.  
18. [MethodImpl(MethodImplOptions.AggressiveInlining)]
19. public static quaternion FromToRotation (float3 fromDirection, float3 toDirection)
20. {
21.     float3 cross = math.cross(fromDirection, toDirection);
22.     float dot = math.dot(fromDirection, toDirection);
23.  
24.     var q = new quaternion(
25.         cross.x,
26.         cross.y,
27.         cross.z,
28.         dot + math.sqrt(math.length(fromDirection) * math.length(toDirection))
29.     );
30.  
31.     return math.normalize(q);
32. }
33.  
34. [MethodImpl(MethodImplOptions.AggressiveInlining)]
35. public static float3 ProjectOnPlane (float3 vector, float3 planeNormal)
36. {
37.     float invSqrMag = 1f / math.dot(planeNormal, planeNormal);
38.     if (math.isnan(invSqrMag))
39.         return vector;
40.     else
41.     {
42.         var dot = math.dot(vector, planeNormal);
43.         return new float3(
44.             vector.x - planeNormal.x * dot * invSqrMag,
45.             vector.y - planeNormal.y * dot * invSqrMag,
46.             vector.z - planeNormal.z * dot * invSqrMag);
47.     }
48. }
49.  
50. [MethodImpl(MethodImplOptions.AggressiveInlining)]
51. public static float Angle (quaternion a, quaternion b)
52. {
53.     float dot = math.min(math.abs(math.dot(a, b)), 1.0f);
54.     return IsEqualUsingDot(dot) ? 0.0f : math.degrees(math.acos(dot) * 2.0f);
55. }
56.  
57. // Is the dot product of two quaternions within tolerance for them to be considered equal?
58. [MethodImpl(MethodImplOptions.AggressiveInlining)]
59. private static bool IsEqualUsingDot (float dot)
60. {
61.     // Returns false in the presence of NaN values.
62.     return dot > 1.0f - epsilon;
63. }
64.  
65.  

 

Some probability distributions would be handy. I keep re-implementing the Gaussian function...