added extra functions

src/main/java/rocks/zipcode/calcskin/CalcEngine.java

@@ -5,19 +5,63 @@ public class CalcEngine {
     CalcEngine() {
     }
 
-    public double add(double v, double v1) {
-        return Double.NaN;
+    public double add(double x, double y) {
+        return x + y;
     }
 
-    public double subtract(double v, double v1) {
-        return Double.NaN;
+    public double subtract(double x, double y) {
+        return x - y;
     }
 
-    public double multiply(double v, double v1) {
-        return Double.NaN;
+    public double multiply(double x, double y) {
+        return x * y;
     }
 
-    public double divide(double v, double v1) {
-        return Double.NaN;
+    public double divide(double x, double y) {
+        return x / y;
+    }
+
+    public double square(double x) {
+        return Math.pow(x, 2.0D);
+    }
+
+    public double squareroot(double x) {
+        return Math.sqrt(x);
+    }
+
+    public double power(double x, double y) {
+        return Math.pow(x, y);
+    }
+
+    public double inverse(double x) {
+        return 1.0D / x;
+    }
+
+    public static double invert(double x) {
+        return -x;
+    }
+
+    public static double findSin(double x) {
+        return Math.sin(x);
+    }
+
+    public static double findCos(double x) {
+        return Math.cos(x);
+    }
+
+    public static double findTan(double x) {
+        return Math.tan(x);
+    }
+
+    public static double findAsin(double x) {
+        return Math.asin(x);
+    }
+
+    public static double findAcos(double x) {
+        return Math.acos(x);
+    }
+
+    public static double findAtan(double x) {
+        return Math.atan(x);
     }
 }

src/main/java/rocks/zipcode/calcskin/CalcSkin.java

@@ -24,10 +24,10 @@ public class CalcSkin extends Application {
         launch(args);
     }
     private static final String[][] template = {
-            { "7", "8", "9", "/" },
-            { "4", "5", "6", "*" },
-            { "1", "2", "3", "-" },
-            { "0", "c", "=", "+" }
+            { "7", "8", "9", "/", "x²" },
+            { "4", "5", "6", "*", "√x" },
+            { "1", "2", "3", "-", "x^" },
+            { "0", "c", "=", "+", "1/x" }
     };
 
     private final Map<String, Button> accelerators = new HashMap<>();
@@ -36,7 +36,7 @@ public class CalcSkin extends Application {
     private DoubleProperty currentValue = new SimpleDoubleProperty();
     private CalcEngine calcEngine = new CalcEngine();
 
-    private enum Op { NOOP, ADD, SUBTRACT, MULTIPLY, DIVIDE }
+    private enum Op { NOOP, ADD, SUBTRACT, MULTIPLY, DIVIDE, SQUARE, SQUAREROOT, POWER, INVERSE }
 
     private Op curOp   = Op.NOOP;
     private Op stackOp = Op.NOOP;
@@ -50,7 +50,7 @@ public class CalcSkin extends Application {
         final TextField screen  = createScreen();
         final TilePane  buttons = createButtons();
 
-        stage.setTitle("Calc");
+        stage.setTitle("Calculator");
         stage.initStyle(StageStyle.UTILITY);
         stage.setResizable(false);
         stage.setScene(new Scene(createLayout(screen, buttons)));
@@ -60,7 +60,7 @@ public class CalcSkin extends Application {
     private VBox createLayout(TextField screen, TilePane buttons) {
         final VBox layout = new VBox(20);
         layout.setAlignment(Pos.CENTER);
-        layout.setStyle("-fx-background-color: silver; -fx-padding: 20; -fx-font-size: 20;");
+        layout.setStyle("-fx-background-color: AQUAMARINE; -fx-padding: 20; -fx-font-size: 20;");
         layout.getChildren().setAll(screen, buttons);
         handleAccelerators(layout);
         screen.prefWidthProperty().bind(buttons.widthProperty());
@@ -81,7 +81,7 @@ public class CalcSkin extends Application {
 
     private TextField createScreen() {
         final TextField screen = new TextField();
-        screen.setStyle("-fx-background-color: aquamarine;");
+        screen.setStyle("-fx-background-color: HONEYDEW;");
         screen.setAlignment(Pos.CENTER_RIGHT);
         screen.setEditable(false);
         screen.textProperty().bind(Bindings.format("%.0f", currentValue));
@@ -127,6 +127,10 @@ public class CalcSkin extends Application {
             case "-": triggerOp.set(Op.SUBTRACT); break;
             case "*": triggerOp.set(Op.MULTIPLY); break;
             case "/": triggerOp.set(Op.DIVIDE);   break;
+            case "x²": triggerOp.set(Op.SQUARE);      break;
+            case "√x": triggerOp.set(Op.SQUAREROOT); break;
+            case "x^": triggerOp.set(Op.POWER); break;
+            case "1/x": triggerOp.set(Op.INVERSE);   break;
         }
         return triggerOp;
     }
@@ -185,6 +189,10 @@ public class CalcSkin extends Application {
                     case SUBTRACT: currentValue.set(calcEngine.subtract(previousValue.get(), currentValue.get())); break;
                     case MULTIPLY: currentValue.set(calcEngine.multiply(previousValue.get(), currentValue.get())); break;
                     case DIVIDE:   currentValue.set(calcEngine.divide(previousValue.get(), currentValue.get())); break;
+                    case SQUARE:    currentValue.set(calcEngine.square(currentValue.get())); break;
+                    case SQUAREROOT:    currentValue.set(calcEngine.squareroot(currentValue.get())); break;
+                    case POWER:     currentValue.set(calcEngine.power(previousValue.get(), currentValue.get())); break;
+                    case INVERSE:      currentValue.set(calcEngine.inverse(currentValue.get())); break;
                 }
             }
         });