Allow fractional exponents

1 files changed, 59 insertions, 28 deletions

diff --git a/src/main/java/sevenUnits/utils/ObjectProduct.java b/src/main/java/sevenUnits/utils/ObjectProduct.java
index 5a29d79..4ed70be 100644
--- a/src/main/java/sevenUnits/utils/ObjectProduct.java
+++ b/src/main/java/sevenUnits/utils/ObjectProduct.java
@@ -35,6 +35,12 @@ import java.util.function.Function;
  */
 public class ObjectProduct<T> implements Nameable {
 	/**
+	 * If {@link #toExponentRounded}'s rounding changes exponents by more than
+	 * this value, a warning will be printed to standard error.
+	 */
+	private static final double ROUND_WARN_THRESHOLD = 1e-12;
+	
+	/**
 	 * Returns an empty ObjectProduct of a certain type
 	 * 
 	 * @param <T> type of objects that can be multiplied
@@ -44,7 +50,7 @@ public class ObjectProduct<T> implements Nameable {
 	public static final <T> ObjectProduct<T> empty() {
 		return new ObjectProduct<>(new HashMap<>());
 	}
-
+	
 	/**
 	 * Gets an {@code ObjectProduct} from an object-to-integer mapping
 	 * 
@@ -57,7 +63,7 @@ public class ObjectProduct<T> implements Nameable {
 			final Map<T, Integer> map) {
 		return new ObjectProduct<>(new HashMap<>(map));
 	}
-
+	
 	/**
 	 * Gets an ObjectProduct that has one of the inputted argument, and nothing
 	 * else.
@@ -73,7 +79,7 @@ public class ObjectProduct<T> implements Nameable {
 		map.put(object, 1);
 		return new ObjectProduct<>(map);
 	}
-
+	
 	/**
 	 * The objects that make up the product, mapped to their exponents. This map
 	 * treats zero as null, and is immutable.
@@ -81,12 +87,12 @@ public class ObjectProduct<T> implements Nameable {
 	 * @since 2019-10-16
 	 */
 	final Map<T, Integer> exponents;
-
+	
 	/**
 	 * The object's name and symbol
 	 */
 	private final NameSymbol nameSymbol;
-
+	
 	/**
 	 * Creates a {@code ObjectProduct} without a name/symbol.
 	 * 
@@ -96,7 +102,7 @@ public class ObjectProduct<T> implements Nameable {
 	ObjectProduct(final Map<T, Integer> exponents) {
 		this(exponents, NameSymbol.EMPTY);
 	}
-
+	
 	/**
 	 * Creates the {@code ObjectProduct}.
 	 * 
@@ -110,7 +116,7 @@ public class ObjectProduct<T> implements Nameable {
 						e -> !Integer.valueOf(0).equals(e.getValue())));
 		this.nameSymbol = nameSymbol;
 	}
-
+	
 	/**
 	 * Calculates the quotient of two products
 	 *
@@ -125,17 +131,17 @@ public class ObjectProduct<T> implements Nameable {
 		final Set<T> objects = new HashSet<>();
 		objects.addAll(this.getBaseSet());
 		objects.addAll(other.getBaseSet());
-
+		
 		// get a list of all exponents
 		final Map<T, Integer> map = new HashMap<>(objects.size());
 		for (final T key : objects) {
 			map.put(key, this.getExponent(key) - other.getExponent(key));
 		}
-
+		
 		// create the product
 		return new ObjectProduct<>(map);
 	}
-
+	
 	// this method relies on the use of ZeroIsNullMap
 	@Override
 	public boolean equals(final Object obj) {
@@ -146,7 +152,7 @@ public class ObjectProduct<T> implements Nameable {
 		final ObjectProduct<?> other = (ObjectProduct<?>) obj;
 		return Objects.equals(this.exponents, other.exponents);
 	}
-
+	
 	/**
 	 * @return immutable map mapping objects to exponents
 	 * @since 2019-10-16
@@ -154,7 +160,7 @@ public class ObjectProduct<T> implements Nameable {
 	public Map<T, Integer> exponentMap() {
 		return this.exponents;
 	}
-
+	
 	/**
 	 * @return a set of all of the base objects with non-zero exponents that make
 	 *         up this dimension.
@@ -163,7 +169,7 @@ public class ObjectProduct<T> implements Nameable {
 	 */
 	public final Set<T> getBaseSet() {
 		final Set<T> dimensions = new HashSet<>();
-
+		
 		// add all dimensions with a nonzero exponent - zero exponents shouldn't
 		// be there in the first place
 		for (final T dimension : this.exponents.keySet()) {
@@ -171,10 +177,10 @@ public class ObjectProduct<T> implements Nameable {
 				dimensions.add(dimension);
 			}
 		}
-
+		
 		return dimensions;
 	}
-
+	
 	/**
 	 * Gets the exponent for a specific dimension.
 	 * 
@@ -186,17 +192,17 @@ public class ObjectProduct<T> implements Nameable {
 	public int getExponent(final T dimension) {
 		return this.exponents.getOrDefault(dimension, 0);
 	}
-
+	
 	@Override
 	public NameSymbol getNameSymbol() {
 		return this.nameSymbol;
 	}
-
+	
 	@Override
 	public int hashCode() {
 		return Objects.hash(this.exponents);
 	}
-
+	
 	/**
 	 * @return true if this product is a single object, i.e. it has one exponent
 	 *         of one and no other nonzero exponents
@@ -214,7 +220,7 @@ public class ObjectProduct<T> implements Nameable {
 		}
 		return oneCount == 1 && !twoOrMore;
 	}
-
+	
 	/**
 	 * Multiplies this product by another
 	 *
@@ -229,17 +235,17 @@ public class ObjectProduct<T> implements Nameable {
 		final Set<T> objects = new HashSet<>();
 		objects.addAll(this.getBaseSet());
 		objects.addAll(other.getBaseSet());
-
+		
 		// get a list of all exponents
 		final Map<T, Integer> map = new HashMap<>(objects.size());
 		for (final T key : objects) {
 			map.put(key, this.getExponent(key) + other.getExponent(key));
 		}
-
+		
 		// create the product
 		return new ObjectProduct<>(map);
 	}
-
+	
 	/**
 	 * Returns this product, but to an exponent
 	 * 
@@ -254,7 +260,32 @@ public class ObjectProduct<T> implements Nameable {
 		}
 		return new ObjectProduct<>(map);
 	}
-
+	
+	/**
+	 * Returns this product to an exponent, where every dimension is rounded to
+	 * the nearest integer.
+	 * 
+	 * This function will send a warning (via {@link System.err}) if the rounding
+	 * significantly changes the value.
+	 *
+	 * @since 2024-08-22
+	 */
+	public ObjectProduct<T> toExponentRounded(final double exponent) {
+		final Map<T, Integer> map = new HashMap<>(this.exponents);
+		for (final T key : this.exponents.keySet()) {
+			final double newExponent = this.getExponent(key) * exponent;
+			if (Math.abs(
+					newExponent - Math.round(newExponent)) > ROUND_WARN_THRESHOLD) {
+				System.err.printf(
+						"Exponent Rounding Warning: Dimension exponents must be integers, so %d ^ %g = %g was rounded to %d.\n",
+						this.getExponent(key), exponent, newExponent,
+						Math.round(newExponent));
+			}
+			map.put(key, (int) Math.round(newExponent));
+		}
+		return new ObjectProduct<>(map);
+	}
+	
 	/**
 	 * Converts this product to a string using the objects'
 	 * {@link Object#toString()} method (or {@link Nameable#getShortName} if
@@ -271,7 +302,7 @@ public class ObjectProduct<T> implements Nameable {
 				.toString(o -> o instanceof Nameable ? ((Nameable) o).getShortName()
 						: o.toString());
 	}
-
+	
 	/**
 	 * Converts this product to a string. The objects that make up this product
 	 * are represented by {@code objectToString}
@@ -283,7 +314,7 @@ public class ObjectProduct<T> implements Nameable {
 	public String toString(final Function<T, String> objectToString) {
 		final List<String> positiveStringComponents = new ArrayList<>();
 		final List<String> negativeStringComponents = new ArrayList<>();
-
+		
 		// for each base object that makes up this object, add it and its exponent
 		for (final T object : this.getBaseSet()) {
 			final int exponent = this.exponents.get(object);
@@ -297,15 +328,15 @@ public class ObjectProduct<T> implements Nameable {
 						objectToString.apply(object), -exponent));
 			}
 		}
-
+		
 		final String positiveString = positiveStringComponents.isEmpty() ? "1"
 				: String.join(" * ", positiveStringComponents);
 		final String negativeString = negativeStringComponents.isEmpty() ? ""
 				: " / " + String.join(" * ", negativeStringComponents);
-
+		
 		return positiveString + negativeString;
 	}
-
+	
 	/**
 	 * @return named version of this {@code ObjectProduct}, using data from
 	 *         {@code nameSymbol}