Reproduction steps:
1. Open the attached file "perlinNoise.zip";
2. Open the scene "test";
3. Enter the Play mode;
4. Observe the Console window;

Actual result: the function Mathf.PerlinNoise (89.5714f, 3234.57f) returns a value which is less than 0.
Expected result: the function Mathf.PerlinNoise should return a value between 0.0f and 1.0f (https://docs.unity3d.com/ScriptReference/Mathf.PerlinNoise.html)

Reproduced with: 5.4.3f1, 5.5.0f3, 5.6.0b5