Comment out debugging output.

src/main/java/org/nwapw/abacus/number/NaiveNumber.java

@@ -93,6 +93,11 @@ public class NaiveNumber implements NumberInterface {
         return this.compareTo(ZERO);
     }
 
+    @Override
+    public int ceiling() {
+        return (int) Math.ceil(value);
+    }
+
     @Override
     public NumberInterface promoteTo(Class<? extends NumberInterface> toClass) {
         if (toClass == this.getClass()) return this;

src/main/java/org/nwapw/abacus/number/NumberInterface.java

@@ -79,6 +79,12 @@ public interface NumberInterface {
      */
     int signum();
 
+    /**
+     * Returns the least integer greater than or equal to the number.
+     * @return the least integer >= the number, if int can hold the value.
+     */
+    int ceiling();
+
     /**
      * Promotes this class to another number class.
      *

src/main/java/org/nwapw/abacus/number/PreciseNumber.java

@@ -1,6 +1,7 @@
 package org.nwapw.abacus.number;
 
 import java.math.BigDecimal;
+import java.math.MathContext;
 import java.math.RoundingMode;
 
 public class PreciseNumber implements NumberInterface {
@@ -49,7 +50,7 @@ public class PreciseNumber implements NumberInterface {
 
     @Override
     public NumberInterface multiply(NumberInterface multiplier) {
-        return new PreciseNumber(value.multiply(((PreciseNumber) multiplier).value));
+        return new PreciseNumber(this.value.multiply(((PreciseNumber) multiplier).value));
     }
 
     @Override
@@ -94,6 +95,11 @@ public class PreciseNumber implements NumberInterface {
         return value.signum();
     }
 
+    @Override
+    public int ceiling() {
+        return (int) Math.ceil(value.doubleValue());
+    }
+
     @Override
     public NumberInterface negate() {
         return new PreciseNumber(value.negate());

src/main/java/org/nwapw/abacus/plugin/StandardPlugin.java

@@ -8,6 +8,8 @@ import org.nwapw.abacus.number.NaiveNumber;
 import org.nwapw.abacus.number.NumberInterface;
 import org.nwapw.abacus.number.PreciseNumber;
 
+import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.function.BiFunction;
 
 /**
@@ -16,6 +18,8 @@ import java.util.function.BiFunction;
  */
 public class StandardPlugin extends Plugin {
 
+    private static HashMap<Class<? extends NumberInterface>, ArrayList<NumberInterface>> factorialLists = new HashMap<Class<? extends NumberInterface>, ArrayList<NumberInterface>>();
+
     /**
      * The addition operator, +
      */
@@ -152,17 +156,40 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            boolean takeReciprocal = params[0].signum() == -1;
-            params[0] = FUNCTION_ABS.apply(params[0]);
-            NumberInterface sum = sumSeries(params[0], StandardPlugin::getExpSeriesTerm, getNTermsExp(getMaxError(params[0]), params[0]));
-            if (takeReciprocal) {
-                sum = NaiveNumber.ONE.promoteTo(sum.getClass()).divide(sum);
+            NumberInterface maxError = getMaxError(params[0]);
+            int n = 0;
+            if(params[0].signum() <= 0){
+                NumberInterface currentTerm = NaiveNumber.ONE.promoteTo(params[0].getClass()), sum = currentTerm;
+                while(FUNCTION_ABS.apply(currentTerm).compareTo(maxError) > 0){
+                    n++;
+                    currentTerm = currentTerm.multiply(params[0]).divide((new NaiveNumber(n)).promoteTo(params[0].getClass()));
+                    sum = sum.add(currentTerm);
+                }
+                return sum;
+            }
+            else{
+                //We need n such that x^(n+1) * 3^ceil(x) <= maxError * (n+1)!.
+                //right and left refer to lhs and rhs in the above inequality.
+                NumberInterface sum = NaiveNumber.ONE.promoteTo(params[0].getClass());
+                NumberInterface nextNumerator = params[0];
+                NumberInterface left = params[0].multiply((new NaiveNumber(3)).promoteTo(params[0].getClass()).intPow(params[0].ceiling())), right = maxError;
+                do{
+                    sum = sum.add(nextNumerator.divide(factorial(params[0].getClass(), n+1)));
+                    n++;
+                    nextNumerator = nextNumerator.multiply(params[0]);
+                    left = left.multiply(params[0]);
+                    NumberInterface nextN = (new NaiveNumber(n+1)).promoteTo(params[0].getClass());
+                    right = right.multiply(nextN);
+                    //System.out.println(left + ", " + right);
+                }
+                while(left.compareTo(right) > 0);
+                //System.out.println(n+1);
+                return sum;
             }
-            return sum;
         }
     };
     /**
-     * The natural log function, ln(exp(1)) = 1
+     * The natural log function.
      */
     public static final Function FUNCTION_LN = new Function() {
         @Override
@@ -239,7 +266,7 @@ public class StandardPlugin extends Plugin {
         }
     };
     /**
-     * The square root function, sqrt(4) = 2
+     * The square root function.
      */
     public static final Function FUNCTION_SQRT = new Function() {
         @Override
@@ -257,39 +284,6 @@ public class StandardPlugin extends Plugin {
         super(manager);
     }
 
-    /**
-     * Returns the nth term of the Taylor series (centered at 0) of e^x
-     *
-     * @param n the term required (n >= 0).
-     * @param x the real number at which the series is evaluated.
-     * @return the nth term of the series.
-     */
-    private static NumberInterface getExpSeriesTerm(int n, NumberInterface x) {
-        return x.intPow(n).divide(OP_FACTORIAL.getFunction().apply((new NaiveNumber(n)).promoteTo(x.getClass())));
-    }
-
-    /**
-     * Returns the number of terms needed to evaluate the exponential function (at x)
-     * such that the error is at most maxError.
-     *
-     * @param maxError Maximum error permissible (This should probably be positive.)
-     * @param x        where the function is evaluated.
-     * @return the number of terms needed to evaluate the exponential function.
-     */
-    private static int getNTermsExp(NumberInterface maxError, NumberInterface x) {
-        //We need n such that |x^(n+1)| <= (n+1)! * maxError
-        //The variables LHS and RHS refer to the above inequality.
-        int n = 0;
-        x = FUNCTION_ABS.apply(x);
-        NumberInterface LHS = x, RHS = maxError;
-        while (LHS.compareTo(RHS) > 0) {
-            n++;
-            LHS = LHS.multiply(x);
-            RHS = RHS.multiply(new NaiveNumber(n + 1).promoteTo(RHS.getClass()));
-        }
-        return n;
-    }
-
     /**
      * Returns a partial sum of a series whose terms are given by the nthTermFunction, evaluated at x.
      *
@@ -339,4 +333,19 @@ public class StandardPlugin extends Plugin {
 
     }
 
+    public static NumberInterface factorial(Class<? extends NumberInterface> numberClass, int n){
+        if(!factorialLists.containsKey(numberClass)){
+            factorialLists.put(numberClass, new ArrayList<NumberInterface>());
+            factorialLists.get(numberClass).add(NaiveNumber.ONE.promoteTo(numberClass));
+            factorialLists.get(numberClass).add(NaiveNumber.ONE.promoteTo(numberClass));
+        }
+        ArrayList<NumberInterface> list = factorialLists.get(numberClass);
+        if(n >= list.size()){
+            while(list.size() < n + 16){
+                list.add(list.get(list.size()-1).multiply(new NaiveNumber(list.size()).promoteTo(numberClass)));
+            }
+        }
+        return list.get(n);
+    }
+
 }