CatlikeCoding 3d graphs

Hey folks,

I'm trying to follow CatlikeCoding's tutorial on 3d graphs in unity. However seems that some features are deprecated. Disclaimer: I'm not terribly experienced with unity. Here's the tutorial: http://catlikecoding.com/unity/tutorials/graphs/#a-questionmark

Rn i'm at this step of the tutorial:

Code (CSharp): void Start () {

     if (resolution < 10 || resolution > 100) {
         Debug.LogWarning ("Grapher resolution is out of bounds, resetting to minimum.", this);
         resolution = 10;
    
         float increment = 1f / (resolution - 1);
         for (int i = 0; i < resolution; i++) {
             float x = i * increment;
             points [i].position = new Vector3 (x, 0f, 0f);
             points [i].color = new Color (x, 0f, 0f);
             points [i].size = 0.1f;
 
         }
         points = new ParticleSystem.Particle[resolution];
 
     }
 }
 // Update is called once per frame
 void Update () {
     particleSystem.SetParticles(points, points.Length);
 
 
 }

}

My error is at the line inside of Update(). This is deprecated. So i replaced it by doing:

particles = GetComponent (); (inside of Start)

Then in update i used: particles.SetParticles(points, points.Length);

However i'm getting an object reference not set to an instance of object error pointing to my Update function. Any help would be appreciated.