Data commit

Task/Metallic-ratios/Java/metallic-ratios.java

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+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.math.MathContext;
+import java.util.ArrayList;
+import java.util.List;
+
+public class MetallicRatios {
+
+    private static String[] ratioDescription = new String[] {"Platinum", "Golden", "Silver", "Bronze", "Copper", "Nickel", "Aluminum", "Iron", "Tin", "Lead"};
+
+    public static void main(String[] args) {
+        int elements = 15;
+        for ( int b = 0 ; b < 10 ; b++ ) {
+            System.out.printf("Lucas sequence for %s ratio, where b = %d:%n", ratioDescription[b], b);
+            System.out.printf("First %d elements: %s%n", elements, lucasSequence(1, 1, b, elements));
+            int decimalPlaces = 32;
+            BigDecimal[] ratio = lucasSequenceRatio(1, 1, b, decimalPlaces+1);
+            System.out.printf("Value to %d decimal places after %s iterations : %s%n", decimalPlaces, ratio[1], ratio[0]);
+            System.out.printf("%n");
+        }
+        int b = 1;
+        int decimalPlaces = 256;
+        System.out.printf("%s ratio, where b = %d:%n", ratioDescription[b], b);
+        BigDecimal[] ratio = lucasSequenceRatio(1, 1, b, decimalPlaces+1);
+        System.out.printf("Value to %d decimal places after %s iterations : %s%n", decimalPlaces, ratio[1], ratio[0]);
+    }
+
+    private static BigDecimal[] lucasSequenceRatio(int x0, int x1, int b, int digits) {
+        BigDecimal x0Bi = BigDecimal.valueOf(x0);
+        BigDecimal x1Bi = BigDecimal.valueOf(x1);
+        BigDecimal bBi = BigDecimal.valueOf(b);
+        MathContext mc = new MathContext(digits);
+        BigDecimal fractionPrior = x1Bi.divide(x0Bi, mc);
+        int iterations = 0;
+        while ( true ) {
+            iterations++;
+            BigDecimal x = bBi.multiply(x1Bi).add(x0Bi);
+            BigDecimal fractionCurrent = x.divide(x1Bi, mc);
+            if ( fractionCurrent.compareTo(fractionPrior) == 0 ) {
+                break;
+            }
+            x0Bi = x1Bi;
+            x1Bi = x;
+            fractionPrior = fractionCurrent;
+        }
+        return new BigDecimal[] {fractionPrior, BigDecimal.valueOf(iterations)};
+    }
+
+    private static List<BigInteger> lucasSequence(int x0, int x1, int b, int n) {
+        List<BigInteger> list = new ArrayList<>();
+        BigInteger x0Bi = BigInteger.valueOf(x0);
+        BigInteger x1Bi = BigInteger.valueOf(x1);
+        BigInteger bBi = BigInteger.valueOf(b);
+        if ( n > 0 ) {
+            list.add(x0Bi);
+        }
+        if ( n > 1 ) {
+            list.add(x1Bi);
+        }
+        while ( n > 2 ) {
+            BigInteger x = bBi.multiply(x1Bi).add(x0Bi);
+            list.add(x);
+            n--;
+            x0Bi = x1Bi;
+            x1Bi = x;
+        }
+        return list;
+    }
+
+}