feat:

* implemented sin & cos function using taylor series approximation, and got tests run for sin & cos successful

Signed-off-by: johnzhouinfo <[email protected]>

src/Assign_2/TrigFunction.java

@@ -6,27 +6,93 @@
  */
 public final class TrigFunction {
 
+    /**
+     * Sin function using Taylor series approximation
+     *
+     * @param angRad radian
+     * @return
+     */
     public static double sin(double angRad) {
-        return 0.0;
+        double radian = convertRadian(angRad);
+        // compute the Taylor series approximation
+        double term = 1.0;  // ith term = x^i / i!
+        double sum = 0.0;  // sum of first i terms in taylor series
+
+        for (int i = 1; term != 0.0; i++) {
+            term *= (radian / i);
+            if (i % 4 == 1) sum += term;
+            if (i % 4 == 3) sum -= term;
+        }
+        return sum;
     }
 
+    /**
+     * Cos function using Taylor series approximation
+     *
+     * @param angRad radian
+     * @return
+     */
     public static double cos(double angRad) {
-        return 0.0;
+        double radian = convertRadian(angRad);
+        // compute the Taylor series approximation
+        double term = 1.0;  // ith term = x^i / i!
+        double sum = 0.0;  // sum of first i terms in taylor series
+
+        for (int i = 1; term != 0.0; i++) {
+            term *= (radian / i);
+            if (i % 4 == 0) sum += term;
+            if (i % 4 == 2) sum -= term;
+        }
+        return 1 + sum;
     }
 
+    /**
+     * Tan function
+     *
+     * @param angRad radian
+     * @return
+     */
     public static double tan(double angRad) {
         return 0.0;
     }
 
+    /**
+     * Cot function
+     *
+     * @param angRad radian
+     * @return
+     */
     public static double cot(double angRad) {
         return 0.0;
     }
 
+    /**
+     * Csc function
+     *
+     * @param angRad radian
+     * @return
+     */
     public static double csc(double angRad) {
         return 0.0;
     }
 
+    /**
+     * Sec function
+     *
+     * @param angRad radian
+     * @return
+     */
     public static double sec(double angRad) {
         return 0.0;
     }
+
+    /**
+     * Convert radian between -2 PI and 2 PI
+     *
+     * @param angRad input radian
+     * @return
+     */
+    private static double convertRadian(double angRad) {
+        return angRad % (2 * Math.PI);
+    }
 }