Reorganised projects

2 files changed, 334 insertions, 0 deletions

diff --git a/Week7 Polynomials/src/polynomial/Polynomial.java b/Week7 Polynomials/src/polynomial/Polynomial.java
new file mode 100644
index 0000000..c87b96a
--- /dev/null
+++ b/Week7 Polynomials/src/polynomial/Polynomial.java
@@ -0,0 +1,189 @@
+package polynomial;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Scanner;
+
+/**
+ * A class for representing Polynomials
+ *
+ * @author Sjaak Smetsers
+ * @date 10-03-2015
+ * 
+ * @author Camil Staps, s4498062
+ * @date 17-03-2015
+ */
+public class Polynomial {
+
+    /**
+     * A polynomial is a sequence of terms here kept in an List.
+     * The assignment tells us 'it's handy' when terms are ordered by exponent.
+     * We don't seem to need that though, so there's no need to implement it.
+     */
+    List<Term> terms;
+
+    /**
+     * A constructor for creating the zero Polynomial zero is presented as an
+     * empty list of terms and not as a single term with 0 as a coefficient
+     */
+    public Polynomial() {
+        terms = new ArrayList<>();
+    }
+
+    /**
+     * A Constructor creating a polynomial from the argument string.
+     * 
+     * This implementation, in contrast to the given implementation, allows for 
+     * entering polynomials with two or more terms with the same exponent. Even 
+     * though this is strictly not necessary and these inputs aren't legit, this
+     * behaviour is always better than the behaviour of the given implementation 
+     * which would happily add two terms with the same exponent to our list.
+     * 
+     * This implementation also directly checks that the coefficient unequals 0,
+     * which is also not need-to-have, but still nice-to-have.
+     * 
+     * Both changes to the given implementation do not change the behaviour on
+     * legit input but do allow a user to mess up in some cases.
+     *
+     * @param s a String representing a list of terms which is converted to a
+     * scanner and passed to scanTerm for reading each individual term
+     */
+    public Polynomial( String s ) {
+        terms = new ArrayList<>();
+        Scanner scan = new Scanner(s);
+
+        for (Term t = Term.scanTerm(scan); t != null; t = Term.scanTerm(scan))
+            if (t.getCoef() != 0)
+                plus(t);
+    }
+
+    /**
+     * The copy constructor for making a deep copy
+     *
+     * @param p the copied polynomial
+     */
+    public Polynomial( Polynomial p ) {
+        terms = new ArrayList<>(p.terms.size());
+        for (Term t : p.terms) {
+            terms.add(new Term(t));
+        }
+    }
+    
+    /**
+     * A straightforward conversion of a Polynomial into a string based on the
+     * toString for terms
+     *
+     * @return a readable string representation of this
+     */
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        boolean not_first = false;
+        for (Term t : terms) {
+            if (not_first && t.getCoef() >= 0) 
+                sb.append("+");
+            sb.append(t);
+            not_first = true;
+        }
+        return sb.toString();
+    }
+
+    /**
+     * Add a polynomial to this polynomial
+     * @param b the polynomial to add
+     */
+    public void plus(Polynomial b) {
+        for (Term t : b.terms)
+            plus(t);
+    }
+    
+    /**
+     * Add a term
+     * @param t the term to add
+     */
+    private void plus(Term t) {
+        if (t.getCoef() == 0)
+            return;
+        
+        Iterator<Term> iter = terms.iterator();
+        while (iter.hasNext()) {
+            Term this_t = iter.next();
+            if (this_t.getExp() == t.getExp()) {
+                this_t.plus(t);
+                if (this_t.getCoef() == 0)
+                    iter.remove();
+                return;
+            }
+        }
+        terms.add(new Term(t));
+    }
+
+    /**
+     * Subtract a polynomial from this polynomial
+     * @param p the polynomial to subtract
+     */
+    public void minus(Polynomial p) {
+        Polynomial temp = new Polynomial(p);
+        temp.times(new Polynomial("-1 0"));
+        plus(temp);
+    }
+
+    /**
+     * Multiply a polynomial with this polynomial
+     * @param p the polynomial to multiply with
+     */
+    public void times(Polynomial p) {
+        Polynomial result = new Polynomial();
+        for (Term that_t : p.terms) 
+            for (Term this_t : terms)
+                result.plus(new Term(that_t.getCoef() * this_t.getCoef(), that_t.getExp() + this_t.getExp()));
+        terms = result.terms;
+    }
+
+    public void divide(Polynomial b) {
+    }
+
+    /**
+     * Check equality
+     * @param other_poly the object to check with
+     * @return true iff other_poly represents the same polynomial as this instance
+     */
+    @Override
+    public boolean equals(Object other_poly) {
+        if (other_poly == null || other_poly.getClass() != getClass())
+            return false;
+        
+        Polynomial that = new Polynomial((Polynomial) other_poly);      // We need to copy because later we'll remove elements
+        if (terms.size() != that.terms.size()) 
+            return false;
+        for (Term this_t : terms) {
+            Iterator<Term> that_iter = that.terms.iterator();
+            boolean found = false;
+            while (that_iter.hasNext()) {
+                if (this_t.equals(that_iter.next())) {
+                    found = true;
+                    that_iter.remove();
+                    break;
+                }
+            }
+            if (!found) {
+                return false;
+            }
+        }
+        return true;
+    }
+    
+    /**
+     * Apply the polynomial to a concrete variable
+     * @param x the variable
+     * @return the result of the polynomial applied on x
+     */
+    public double apply(double x) {
+        double result = 0;
+        for (Term t : terms)
+            result += t.apply(x);
+        return result;
+    }
+
+}
diff --git a/Week7 Polynomials/src/polynomial/Term.java b/Week7 Polynomials/src/polynomial/Term.java
new file mode 100644
index 0000000..60c6381
--- /dev/null
+++ b/Week7 Polynomials/src/polynomial/Term.java
@@ -0,0 +1,145 @@
+package polynomial;
+
+import java.util.Scanner;
+
+/**
+ * For representing terms in a polynomial.
+ *
+ * @author Sjaak Smetsers
+ * @version 1.0
+ * @date 15-02-2012
+ * 
+ * @author Camil Staps, s4498062
+ * @date 17-03-2015
+ */
+public class Term {
+
+    /**
+     * Each term consists of a coefficient and an exponent
+     */
+    private double coefficient;
+    private int exponent;
+
+    /**
+     * a get-method for the exponent
+     *
+     * @return exponent
+     */
+    public int getExp() {
+        return exponent;
+    }
+
+    /**
+     * a get-method for the coefficient
+     *
+     * @return coefficient
+     */
+    public double getCoef() {
+        return coefficient;
+    }
+
+    /**
+     * A two-argument constructor
+     *
+     * @param c the value for the coefficient
+     * @param e the value for the exponent
+     */
+    public Term(double c, int e) {
+        coefficient = c;
+        exponent = e;
+    }
+
+    /**
+     * A copy-constructor
+     *
+     * @param t the term to be copied
+     */
+    public Term(Term t) {
+        this(t.coefficient, t.exponent);
+    }
+
+    /**
+     * For adding two terms with equal exponents
+     *
+     * @param t the term added to this
+     * @require exponent == t.exponent
+     */
+    public void plus(Term t) {
+        coefficient += t.coefficient;
+    }
+
+    /**
+     * For multiplying two terms
+     *
+     * @param t the multiplier
+     */
+    public void times(Term t) {
+        exponent += t.exponent;
+        coefficient *= t.coefficient;
+    }
+
+    /**
+     * Converts a term into a readable representation the standard format is
+     * %fx^%d
+     * I changed the implementation to remove trailing zeroes from the coefficient.
+     *
+     * @return the string representing the term
+     */
+    @Override
+    public String toString() {
+        String nice_coefficient = Double.toString(coefficient);
+        if (Math.round(coefficient) == coefficient)
+            nice_coefficient =  Integer.toString((int) coefficient);
+        if (exponent == 0) {
+            return String.format("%s", nice_coefficient, exponent);
+        } else if (exponent == 1) {
+            return String.format("%sx", nice_coefficient, exponent);
+        } else {
+            return String.format("%sx^%d", nice_coefficient, exponent);
+        }
+    }
+
+    /**
+     * Standard implementation of equality
+     * @param may_be_term the object to check equality with
+     * @return true iff may_be_term represents the same term as this term
+     */
+    @Override
+    public boolean equals(Object may_be_term) {
+        if (may_be_term == null || getClass() != may_be_term.getClass()) {
+            return false;
+        } else {
+            Term term = (Term) may_be_term;
+            return exponent == term.exponent
+                    && coefficient == term.coefficient;
+        }
+    }
+    
+    /**
+     * Apply a term to a concrete variable
+     * @param x the variable to apply the term to
+     * @return the result of the application of the term to x
+     */
+    public double apply(double x) {
+        return coefficient * Math.pow(x, exponent);
+    }
+
+    /**
+     * A static method for converting scanner input into a term. The expected
+     * format is two numbers (coef, exp) separated by whitespaces. The coef
+     * should be either an integer or a decimal number. The exp is an integer.
+     *
+     * @param s the scanner providing the input
+     * @return null if no term could be found, the found term otherwise
+     */
+    public static Term scanTerm(Scanner s) {
+        String coef_patt = "\\-?\\d+(\\.\\d+)?";
+        if (s.hasNext(coef_patt)) {
+            String coef = s.next(coef_patt);
+            int exp = s.nextInt();
+            return new Term(Double.parseDouble(coef), exp);
+        } else {
+            return null;
+        }
+    }
+}