diff --git a/9-1.html b/9-1.html
index d24e0b4..7c943b5 100644
--- a/9-1.html
+++ b/9-1.html
@@ -21,11 +21,19 @@
             canvas {
                 position: absolute;
             }
+
+            .slideContainer {
+                position: relative;
+            }
         </style>
     </head>
     <body>       
         <canvas id="myCanvas" width="1" height="1" style="border:1px solid #ffffff;">
         Your browser does not support the HTML5 canvas tag.</canvas>
+        <div class="slidecontainer">
+            <t>R</t>
+            <input type="range" min="0" max="1" value="0.3" step = ".05" id="rSlider">
+        </div>
         
         <script>
         var c = document.getElementById("myCanvas");
@@ -43,18 +51,30 @@
         ctx.translate(ctx.canvas.width / 2, ctx.canvas.height / 2)
         ctx.scale(3, -3);
 
+        rSlider.oninput = function()
+        {
+           r = parseFloat(this.value);
+           generateArrays();
+           m = 0;
+        }
+
         var y1 = new Array(nn + 1);
         var y2 = new Array(nn + 1);
-        for (n = 0; n < nn + 1; n++)
+
+        function generateArrays()
         {
-            y1[n] = new Array(mm + 1);
-            y2[n] = new Array(mm + 1);
-            for (m = 0; m < mm + 1; m++)
+            for (n = 0; n < nn + 1; n++)
             {
-                y1[n][m] = 10 * Math.cos(2 * Math.PI * (n / nn - m / mm));
-                y2[n][m] = 10 * r * Math.cos(2 * Math.PI * (n / nn + m / mm));
+                y1[n] = new Array(mm + 1);
+                y2[n] = new Array(mm + 1);
+                for (m = 0; m < mm + 1; m++)
+                {
+                    y1[n][m] = 10 * Math.cos(2 * Math.PI * (n / nn - m / mm));
+                    y2[n][m] = 10 * r * Math.cos(2 * Math.PI * (n / nn + m / mm));
+                }
             }
         }
+        generateArrays();
 
         function Clear(ctx)
         {
