Implementation with limited tests; no javadoc yet

2 files changed, 62 insertions, 4 deletions

diff --git a/Week7/src/polynomial/Polynomial.java b/Week7/src/polynomial/Polynomial.java
index 3b327f4..2a1b28e 100644
--- a/Week7/src/polynomial/Polynomial.java
+++ b/Week7/src/polynomial/Polynomial.java
@@ -1,6 +1,7 @@
 package polynomial;
 
 import java.util.ArrayList;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Scanner;
 
@@ -61,18 +62,47 @@ public class Polynomial {
      */
     @Override
     public String toString() {
-        return null;
+        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();
     }
 
     public void plus(Polynomial b) {
+        for (Term t : b.terms)
+            plus(t);
+    }
+    
+    public void plus(Term t) {
+        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(t);
     }
-
 
     public void minus(Polynomial b) {
+        b.times(new Polynomial("-1 0"));
+        plus(b);
     }
 
-
     public void times(Polynomial b) {
+        Polynomial result = new Polynomial();
+        for (Term that_t : b.terms) 
+            for (Term this_t : terms)
+                result.plus(new Polynomial((that_t.getCoef() * this_t.getCoef()) + " " + (that_t.getExp() + this_t.getExp())));
+        terms = result.terms;
     }
 
     public void divide(Polynomial b) {
@@ -80,7 +110,31 @@ public class Polynomial {
 
     @Override
     public boolean equals(Object other_poly) {
-        return false;
+        Polynomial that = (Polynomial) other_poly;
+        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;
+    }
+    
+    public double apply(double x) {
+        double result = 0;
+        for (Term t : terms)
+            result += t.apply(x);
+        return result;
     }
 
 }
diff --git a/Week7/src/polynomial/Term.java b/Week7/src/polynomial/Term.java
index 67bcf04..b8d9f16 100644
--- a/Week7/src/polynomial/Term.java
+++ b/Week7/src/polynomial/Term.java
@@ -105,6 +105,10 @@ public class Term {
                     && coefficient == term.coefficient;
         }
     }
+    
+    public double apply(double x) {
+        return coefficient * Math.pow(x, exponent);
+    }
 
     /**
      * A static method for converting scanner input into a term. The expected