diff options
Diffstat (limited to 'src/de/lmu/ifi/dbs/elki/data/RationalNumber.java')
| -rw-r--r-- | src/de/lmu/ifi/dbs/elki/data/RationalNumber.java | 122 |
1 files changed, 13 insertions, 109 deletions
diff --git a/src/de/lmu/ifi/dbs/elki/data/RationalNumber.java b/src/de/lmu/ifi/dbs/elki/data/RationalNumber.java index 5b2e08fa..cf388481 100644 --- a/src/de/lmu/ifi/dbs/elki/data/RationalNumber.java +++ b/src/de/lmu/ifi/dbs/elki/data/RationalNumber.java @@ -23,11 +23,7 @@ package de.lmu.ifi.dbs.elki.data; along with this program. If not, see <http://www.gnu.org/licenses/>. */ -import java.io.File; -import java.io.FileNotFoundException; -import java.io.PrintStream; import java.math.BigInteger; -import java.util.Random; /** * RationalNumber represents rational numbers in arbitrary precision. Note that @@ -74,7 +70,7 @@ public class RationalNumber extends Number implements Arithmetic<RationalNumber> * @throws IllegalArgumentException if {@link BigInteger#equals(Object) * denominator.equals(}{@link BigInteger#ZERO BigInteger.ZERO)} */ - public RationalNumber(final BigInteger numerator, final BigInteger denominator) throws IllegalArgumentException { + public RationalNumber(final BigInteger numerator, final BigInteger denominator) { if(denominator.equals(BigInteger.ZERO)) { throw new IllegalArgumentException("denominator is 0"); } @@ -113,6 +109,17 @@ public class RationalNumber extends Number implements Arithmetic<RationalNumber> } /** + * Constructs a RationalNumber out of the given double number. + * + * @param number a double number to be represented as a RationalNumber + * @throws IllegalArgumentException if the given Double is infinit or not a + * number + */ + public RationalNumber(final double number) throws IllegalArgumentException { + this(Double.toString(number)); + } + + /** * Constructs a RationalNumber for a given String representing a double. * * @param doubleString a String representing a double number @@ -147,7 +154,7 @@ public class RationalNumber extends Number implements Arithmetic<RationalNumber> power -= fractionalPart.length(); denominator = BigInteger.ONE; // translate power notation - StringBuffer multiplicandString = new StringBuffer("1"); + StringBuilder multiplicandString = new StringBuilder("1"); for(int i = 0; i < Math.abs(power); i++) { multiplicandString.append('0'); } @@ -389,107 +396,4 @@ public class RationalNumber extends Number implements Arithmetic<RationalNumber> public RationalNumber copy() { return new RationalNumber(numerator, denominator); } - - /** - * Compares doubles and RationalNumbers wrt efficiency and accuracy. - * - * @param n the number of random numbers - * @param out target to print results to - */ - public static void test(final int n, final PrintStream out) { - Random rnd = new Random(); - int[] testNumbers1 = new int[n]; - int[] testNumbers2 = new int[n]; - RationalNumber[] rationalNumbers = new RationalNumber[n]; - double[] doubles = new double[n]; - - for(int i = 0; i < n; i++) { - testNumbers1[i] = rnd.nextInt(); - int second = rnd.nextInt(); - while(second == 0) { - second = rnd.nextInt(); - } - testNumbers2[i] = second; - rationalNumbers[i] = new RationalNumber(testNumbers1[i], testNumbers2[i]); - doubles[i] = (double) testNumbers1[i] / (double) testNumbers2[i]; - } - - long doubleStart = System.currentTimeMillis(); - for(int i = 0; i < n; i++) { - doubles[i] = doubles[i] * 7.0 / 5.0 * 5.0 / 7.0 * testNumbers2[i]; - } - long doubleTime = System.currentTimeMillis() - doubleStart; - long rnStart = System.currentTimeMillis(); - for(int i = 0; i < n; i++) { - rationalNumbers[i] = rationalNumbers[i].times(new RationalNumber(7, 1)).divided(new RationalNumber(5, 1)).times(new RationalNumber(5, 1)).divided(new RationalNumber(7, 1)).times(new RationalNumber(testNumbers2[i], 1)); - } - long rnTime = System.currentTimeMillis() - rnStart; - out.println("Efficiency: "); - out.println(" time required for a predefined sequence of operations on " + n + " random numbers:"); - out.println(" double: " + doubleTime); - out.println(" RationalNumber: " + rnTime); - int accuracyDouble = n; - double deviationDouble = 0.0; - int accuracyRN = n; - double deviationRN = 0.0; - for(int i = 0; i < n; i++) { - if((int) doubles[i] != testNumbers1[i]) { - accuracyDouble--; - deviationDouble += testNumbers1[i] - doubles[i]; - } - if(rationalNumbers[i].intValue() != testNumbers1[i]) { - accuracyRN--; - deviationRN += testNumbers1[i] - rationalNumbers[i].doubleValue(); - } - } - out.println("\nAccuracy: "); - out.println(" percentage of correctly recomputed " + n + " random numbers for a sequence of predefined operations:"); - out.println(" double: " + (double) accuracyDouble / (double) n); - out.println(" RationalNumber: " + (double) accuracyRN / (double) n); - out.println(" average deviation:"); - out.println(" double: " + deviationDouble / n); - out.println(" RationalNumber: " + deviationRN / n); - - out.print("Overview:\n--------------------------------------------\n"); - for(int i = 0; i < n; i++) { - out.print("target: "); - out.print((double) testNumbers1[i]); - out.print("\ndouble: "); - out.print(doubles[i]); - out.print("\nrationalnr: "); - out.print(rationalNumbers[i].doubleValue()); - out.print("\n--------------------------------------------\n"); - } - } - - /** - * Calls test for a given number of numbers and a optionally given target - * file. - * - * @param args <int> [<filename>] - */ - public static void main(String[] args) { - try { - int numbers = Integer.parseInt(args[0]); - PrintStream out; - try { - out = new PrintStream(new File(args[1])); - } - catch(FileNotFoundException e) { - System.err.println(e.getMessage()); - System.err.println("printing output to STDOUT"); - out = System.out; - } - catch(ArrayIndexOutOfBoundsException e) { - out = System.out; - } - test(numbers, out); - } - catch(Exception e) { - System.err.print("Usage:\njava "); - System.err.print(RationalNumber.class.getName()); - System.err.println(" <numberOfTestnumbers> [<filename>]"); - System.err.println("If <filename> is ommitted, output will be printed to STDOUT."); - } - } }
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