Mathf.NegativeInfinity unexpectly converts to PositiveInfinity

Hello, basically, I have a mouse-look script, where you can set the limits of view (e.g. you can't circle vertically). But I want to add a horizontal limit too, which is, by default, infinity. And I ran into a problem, when I initialize a minimum X rotation limit to negative infinity (that shows correctly in the inspector), in Awake function, it prints positive infinity.
Here is my code:
using UnityEngine; using System.Collections;

 [AddComponentMenu("Camera-Control/Mouse-Look")]
 public class PlayerCameraController : MonoBehaviour {
     [Space(-10)]
     [Header("Sensitivity")]
     [Space()]
 
     public float sensitivityX = 15f;
     public float sensitivityY = 15f;
 
     [Header("Rotation limits", order=3)]
     [Space(-10, order=4)]
     [Header("  X", order=5)]
     [Space(order=6)]
 
     public float maximalRotationX = Mathf.Infinity;
     public float minimalRotationX = Mathf.NegativeInfinity;
 
     [Space(-10, order=7)]
     [Header("  Y", order=8)]
     [Space(order=9)]
 
     public float maximalRotationY = 90f;
     public float minimalRotationY = -90f;
 
     private float oldX;
     private float oldY;
 
     private Quaternion originalRotation;
 
     void Awake () {
         float a = Mathf.NegativeInfinity;
 
         print (a);
 
         originalRotation = transform.localRotation;
 
         oldX = originalRotation.x;
         oldY = originalRotation.y;
     }
 
     void UpdateRotation () {
         float rX = Mathf.Clamp (Input.GetAxis ("Mouse X") * sensitivityX, -360f, 360f) + oldX;
         float rY = Mathf.Clamp (Input.GetAxis ("Mouse Y") * sensitivityY, -360f, 360f) + oldY;
 
         rX = rX <= maximalRotationX && rX >= minimalRotationX ? rX : oldX;
         rY = rY <= maximalRotationY && rY >= minimalRotationY ? rY : oldY;
 
         Quaternion qX = Quaternion.AngleAxis (rX, Vector3.up);
         Quaternion qY = Quaternion.AngleAxis (rY, Vector3.left);
 
         transform.localRotation = qX * qY;
 
         oldX = rX;
         oldY = rY;
     }
 
     void FixedUpdate () {
         UpdateRotation ();
     }
 }
 

Any ideas?