Simplify 3-D Plot (C#) folder structure

87_3-D_Plot/csharp/Function.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+
+namespace Plot
+{
+    internal static class Function
+    {
+        internal static IEnumerable<IEnumerable<int>> GetRows()
+        {
+            for (var x = -30f; x <= 30f; x += 1.5f)
+            {
+                yield return GetValues(x);
+            }
+        }
+
+        private static IEnumerable<int> GetValues(float x)
+        {
+            var zPrevious = 0;
+            var yLimit = 5 * (int)(Math.Sqrt(900 - x * x) / 5);
+
+            for (var y = yLimit; y >= -yLimit; y -= 5)
+            {
+                var z = GetValue(x, y);
+
+                if (z > zPrevious)
+                {
+                    zPrevious = z;
+                    yield return z;
+                }
+            }
+        }
+
+        private static int GetValue(float x, float y)
+        {
+            var r = (float)Math.Sqrt(x * x + y * y);
+            return (int)(25 + 30 * Math.Exp(-r * r / 100) - 0.7f * y);
+        }
+    }
+}