Perlin Noise Questions

Ok, so I've been experimenting with perlin noise and haven't had that much luck. I find there aren't many tutorials out their and articles such as this and this don't really go into enough detail. Anyway here's my problem:

I took the first article's script I linked and converted it into UnityScript:

 var width : int;
 var height : int;
 var octaves : int;
 var persistence : float;
 
 function Start(){
     PerlinNoise();
 }
 
 function PerlinNoise(){
     var texture = new Texture2D(width, height, TextureFormat.ARGB32, false);
 
     for(i = 0; i < octaves; i++){
         var frequency = Mathf.Pow(2, i);
         var amplitude = Mathf.Pow(persistence, i);
         for(x = 0; x <= width; x++){
             for(y = 0; y <= height; y++){
                 var noise = InterpolatedNoise(x * frequency, y * frequency) * amplitude;
                 var perlinColor = Color(noise, noise, noise, 0);
                 texture.SetPixel(x, y, perlinColor);
             }
         }
     }
 
     texture.Apply();
     renderer.material.mainTexture = texture;
 }
 
 function InterpolatedNoise(x : int, y : int){
     var initX = x;
     var fractionX = x - initX;
     var initY = y;
     var fractionY = y - initY;
 
     var v1 = SmoothNoise(initX, initY);
     var v2 = SmoothNoise(initX + 1, initY);
     var v3 = SmoothNoise(initX, initY + 1);
     var v4 = SmoothNoise(initX + 1, initY + 1);
 
     var i1 = Interpolate(v1, v2, fractionX);
     var i2 = Interpolate(v3, v4, fractionX);
 
     return Interpolate(i1, i2, fractionY);
 }
 
 function SmoothNoise(x : float, y : float){
     corners = (Noise(x-1, y-1)+Noise(x+1, y-1)+Noise(x-1, y+1)+Noise(x+1, y+1))/16;
     sides   = (Noise(x-1, y)+Noise(x+1, y)+Noise(x, y-1)+Noise(x, y+1))/ 8;
     center  =  Noise(x, y)/4;
     return corners + sides + center;
 }
 
 function Interpolate(a : float, b : float, x : float){
     ft = x * 3.1415927;
     f = (1 - Mathf.Cos(ft)) * 0.5;
 
     return  a*(1-f) + b*f;
 }
 
 function Noise(x : int, y : int){
     var n = x + y * 57;
     n = (n<<13) ^ n;
     var res = (1.0 - ((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0);
     return res;
 }

After doing that I wasn't surprised to find this function gave me a number overflow error:

 function Noise(x : int, y : int){
     var n = x + y * 57;
     n = (n<<13) ^ n;
     var res = (1.0 - ((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0);
     return res;
 }

I figured I would just use the random method, just to see what would happen. I know it's not pseudo but I figured at least something random would show up. After doing that I got this picture. Although It looks cool it obviously isn't perlin noise.

So basically what did I do wrong? My logic is telling me that the pixels are in that pattern because the random method inside the function I replaced isn't perlin. I can't use the other function though because it throws me a number overflow error as explained before. So what's a good perlin number generator that doesn't give me an error, or is their more to this? Could someone please help me out I want to be able to create noise like this.

Thanks!