Implemented MCD

src/main/java/org/nevec/rjm/BigIntegerMath.java

@@ -138,7 +138,8 @@ public class BigIntegerMath {
 	}
 
 	/**
-	 * Compute the list of positive divisors.
+	 * Compute the list of positive divisors.<br>
+	 * <b>Deprecated: This function is extremely slow and inefficient!</b>
 	 * 
 	 * @param n
 	 *            The integer of which the divisors are to be found.
@@ -146,6 +147,7 @@ public class BigIntegerMath {
 	 * @since 2010-08-27
 	 * @author Richard J. Mathar
 	 */
+	@Deprecated
 	static public Vector<BigInteger> divisors(final BigInteger n) {
 		return (new Ifactor(n.abs())).divisors();
 	}

src/main/java/org/warp/picalculator/Main.java

@@ -1,9 +1,16 @@
 package org.warp.picalculator;
 
+import java.math.BigInteger;
+import java.util.LinkedList;
+import java.util.Vector;
+
+import org.nevec.rjm.BigIntegerMath;
 import org.warp.picalculator.device.Keyboard;
 import org.warp.picalculator.gui.DisplayManager;
 import org.warp.picalculator.gui.screens.LoadingScreen;
 import org.warp.picalculator.gui.screens.Screen;
+import org.warp.picalculator.math.MathContext;
+import org.warp.picalculator.math.functions.Number;
 
 import com.pi4j.system.SystemInfo.BoardType;
 import com.pi4j.wiringpi.Gpio;
@@ -56,6 +63,69 @@ public class Main {
 	}
 
 	public static void main(String[] args) throws InterruptedException {
+		/*
+		 * TEST: Comparing BigIntegerMath.divisors() vs programmingpraxis' Number.getFactors() function
+		 * 
+		long time1;
+		long time2;
+		final int max = 10000;
+		final long HCN = 720720L;
+		final long LCN = 104911L;
+		final BigInteger[] bigintegers = new BigInteger[max];
+		bigintegers[0] = BigInteger.valueOf(HCN);
+		for (int i = 0; i < max; i++) {
+			bigintegers[i] = bigintegers[0];
+		}
+		final Number[] numbers = new Number[max];
+		final MathContext mc = new MathContext();
+		numbers[0] = new Number(mc, HCN);
+		for (int i = 0; i < max; i++) {
+			numbers[i] = numbers[0];
+		}
+		Vector<BigInteger> empty = null;
+		LinkedList<BigInteger> empty2 = null;
+		
+		time1 = System.currentTimeMillis();
+		for(int i = 0; i < max; i++) {
+			empty = BigIntegerMath.divisors(bigintegers[i]);
+		}
+		time2 = System.currentTimeMillis();
+		System.out.println("BigIntegerMath HCN: "+(time2-time1)+" ("+empty.toString()+")");
+		
+
+		bigintegers[0] = BigInteger.valueOf(LCN);
+		for (int i = 0; i < max; i++) {
+			bigintegers[i] = bigintegers[0];
+		}
+		
+		time1 = System.currentTimeMillis();
+		for(int i = 0; i < max; i++) {
+			empty = BigIntegerMath.divisors(bigintegers[i]);
+		}
+		time2 = System.currentTimeMillis();
+		System.out.println("BigIntegerMath LCN: "+(time2-time1)+" ("+empty.toString()+")");
+		
+		time1 = System.currentTimeMillis();
+		for(int i = 0; i < max; i++) {
+			empty2 = numbers[i].getFactors();
+		}
+		time2 = System.currentTimeMillis();
+		System.out.println("BigIntegerMath HCN: "+(time2-time1)+" ("+empty2.toString()+")");
+
+		numbers[0] = new Number(mc, LCN);
+		for (int i = 0; i < max; i++) {
+			numbers[i] = numbers[0];
+		}
+		time1 = System.currentTimeMillis();
+		for(int i = 0; i < max; i++) {
+			empty2 = numbers[i].getFactors();
+		}
+		time2 = System.currentTimeMillis();
+		System.out.println("BigIntegerMath LCN: "+(time2-time1)+" ("+empty2.toString()+")");
+		if(true) {
+			System.exit(0);;
+		}
+		*/
 		new Main(args);
 	}
 }

src/main/java/org/warp/picalculator/math/functions/Division.java

@@ -1,5 +1,9 @@
 package org.warp.picalculator.math.functions;
 
+import java.math.BigInteger;
+import java.util.LinkedList;
+
+import org.nevec.rjm.BigIntegerMath;
 import org.warp.picalculator.Error;
 import org.warp.picalculator.gui.expression.blocks.Block;
 import org.warp.picalculator.gui.expression.blocks.BlockChar;
@@ -49,7 +53,15 @@ public class Division extends FunctionOperator {
 		if (variable1 instanceof Number && variable2 instanceof Number) {
 			if (getMathContext().exactMode) {
 				try {
-					return ((Number) variable1).divide((Number) variable2).isInteger();
+					if (((Number) variable1).isInteger() && ((Number) variable2).isInteger()) {
+						LinkedList<BigInteger> factors1 = ((Number) variable1).getFactors();
+						LinkedList<BigInteger> factors2 = ((Number) variable2).getFactors();
+						return factors1.retainAll(factors2); //True If something changed in the factors list by keeping only the intersection of the two factor lists.
+					} else if (((Number) variable1).divide((Number) variable2).isInteger()) {
+						return true;
+					} else {
+						return false;
+					}
 				} catch (final Error e) {
 					return false;
 				}
@@ -78,7 +90,21 @@ public class Division extends FunctionOperator {
 		} else if (UndefinedRule2.compare(this)) {
 			result = UndefinedRule2.execute(this);
 		} else if (variable1 instanceof Number && variable2 instanceof Number) {
-			result.add(((Number) variable1).divide((Number) variable2));
+			if (getMathContext().exactMode && (((Number) variable1).isInteger() && ((Number) variable2).isInteger())) {
+				LinkedList<BigInteger> factors1 = ((Number) variable1).getFactors();
+				LinkedList<BigInteger> factors2 = ((Number) variable2).getFactors();
+				if(factors1.retainAll(factors2)) { //True If something changed in the factors list by keeping only the intersection of the two factor lists.
+					BigInteger nmb1 = ((Number) this.getParameter1()).term.toBigIntegerExact();
+					BigInteger nmb2 = ((Number) this.getParameter2()).term.toBigIntegerExact();
+					for (BigInteger i : factors1) {
+						nmb1 = nmb1.divide(i);
+						nmb2 = nmb2.divide(i);
+					}
+					result.add(new Division(mathContext, new Number(mathContext, nmb1), new Number(mathContext, nmb2)));
+				}
+			} else {
+				result.add(((Number) variable1).divide((Number) variable2));
+			}
 		}
 		return result;
 	}

src/main/java/org/warp/picalculator/math/functions/Number.java

@@ -194,7 +194,11 @@ public class Number implements Function {
 		}
 		return false;
 	}
-
+	
+	/**
+	 * @author programmingpraxis
+	 * @return
+	 */
 	public LinkedList<BigInteger> getFactors() {
 		BigInteger n = getTerm().toBigIntegerExact();
 		final BigInteger two = BigInteger.valueOf(2);