Add some tests to pow.

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

@@ -128,5 +128,9 @@ public class NaiveNumber extends NumberInterface {
         return Double.toString(Math.round(value * shiftBy) / shiftBy);
     }
 
+    @Override
+    public NumberInterface getMaxError(){
+        return new NaiveNumber(Math.pow(10, -18));
+    }
 }
 

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

@@ -182,7 +182,7 @@ public abstract class NumberInterface {
      * Also, checks if the thread has been interrupted, and if so, throws
      * an exception.
      *
-     * @return the least integer bigger or equal to the number, if int can hold the value.
+     * @return the least integer bigger or equal to the number.
      */
     public final NumberInterface ceiling(){
         checkInterrupted();
@@ -192,7 +192,7 @@ public abstract class NumberInterface {
     /**
      * Return the greatest integer less than or equal to the number.
      *
-     * @return the greatest integer smaller or equal the number, if int can hold the value.
+     * @return the greatest integer smaller or equal the number.
      */
     protected abstract NumberInterface floorInternal();
 
@@ -201,7 +201,7 @@ public abstract class NumberInterface {
      * Also, checks if the thread has been interrupted, and if so, throws
      * an exception.
      *
-     * @return the greatest int smaller or equal to the number, if int can hold the value.
+     * @return the greatest int smaller than or equal to the number.
      */
     public final NumberInterface floor(){
         checkInterrupted();
@@ -216,7 +216,7 @@ public abstract class NumberInterface {
     protected abstract NumberInterface fractionalPartInternal();
 
     /**
-     * Returns the fractional part of the number.
+     * Returns the fractional part of the number, specifically x - floor(x).
      * Also, checks if the thread has been interrupted,
      * and if so, throws an exception.
      * @return the fractional part of the number.
@@ -255,4 +255,11 @@ public abstract class NumberInterface {
         return promoteToInternal(toClass);
     }
 
+    /**
+     * Returns the smallest error this instance can tolerate depending
+     * on its precision and value.
+     * @return the smallest error that should be permitted in calculations.
+     */
+    public abstract NumberInterface getMaxError();
+
 }

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

@@ -1,7 +1,7 @@
 package org.nwapw.abacus.number;
 
 import java.math.BigDecimal;
-import java.math.RoundingMode;
+import java.math.MathContext;
 
 /**
  * A number that uses a BigDecimal to store its value,
@@ -22,6 +22,21 @@ public class PreciseNumber extends NumberInterface {
      */
     public static final PreciseNumber TEN = new PreciseNumber(BigDecimal.TEN);
 
+    /**
+     * The number of extra significant figures kept in calculations before rounding for output.
+     */
+    private static int numExtraInternalSigFigs = 15;
+
+    /**
+     * MathContext that is used when rounding a number prior to output.
+     */
+    private static MathContext outputContext = new MathContext(50);
+
+    /**
+     * MathContext that is actually used in calculations.
+     */
+    private static MathContext internalContext = new MathContext(outputContext.getPrecision()+numExtraInternalSigFigs);
+
     /**
      * The value of the PreciseNumber.
      */
@@ -48,7 +63,7 @@ public class PreciseNumber extends NumberInterface {
 
     @Override
     public int getMaxPrecision() {
-        return 65;
+        return internalContext.getPrecision();
     }
 
     @Override
@@ -58,7 +73,7 @@ public class PreciseNumber extends NumberInterface {
 
     @Override
     public NumberInterface divideInternal(NumberInterface divisor) {
-        return new PreciseNumber(value.divide(((PreciseNumber) divisor).value, this.getMaxPrecision(), RoundingMode.HALF_UP));
+        return new PreciseNumber(value.divide(((PreciseNumber) divisor).value, internalContext));
     }
 
     @Override
@@ -113,19 +128,18 @@ public class PreciseNumber extends NumberInterface {
         String str = value.toPlainString();
         int decimalIndex = str.indexOf('.');
         if (decimalIndex != -1) {
-            return new PreciseNumber(str.substring(0, decimalIndex));
+            NumberInterface floor = new PreciseNumber(str.substring(0, decimalIndex));
+            if(signum() == -1){
+                floor = floor.subtract(ONE);
+            }
+            return floor;
         }
         return this;
     }
 
     @Override
     public NumberInterface fractionalPartInternal() {
-        String str = value.toPlainString();
+        return this.subtractInternal(floorInternal());
-        int decimalIndex = str.indexOf('.');
-        if (decimalIndex != -1) {
-            return new PreciseNumber(str.substring(decimalIndex + 1));
-        }
-        return ZERO;
     }
 
     @Override
@@ -148,7 +162,11 @@ public class PreciseNumber extends NumberInterface {
 
     @Override
     public String toString() {
-        BigDecimal rounded = value.setScale(getMaxPrecision() - 15, RoundingMode.HALF_UP);
+        return value.round(outputContext).toString();
-        return rounded.stripTrailingZeros().toPlainString();
+    }
+
+    @Override
+    public NumberInterface getMaxError(){
+        return new PreciseNumber(value.ulp()).multiplyInternal(TEN.intPowInternal(value.precision()-internalContext.getPrecision()));
     }
 }

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

@@ -188,7 +188,7 @@ public class StandardPlugin extends Plugin {
          */
         private NumberInterface getLogPartialSum(NumberInterface x) {
 
-            NumberInterface maxError = getMaxError(x);
+            NumberInterface maxError = x.getMaxError();
             x = x.subtract(NaiveNumber.ONE.promoteTo(x.getClass())); //Terms used are for log(x+1).
             NumberInterface currentNumerator = x, currentTerm = x, sum = x;
             int n = 1;
@@ -207,7 +207,7 @@ public class StandardPlugin extends Plugin {
          * @return the value of log(2) with the appropriate precision.
          */
         private NumberInterface getLog2(NumberInterface number) {
-            NumberInterface maxError = getMaxError(number);
+            NumberInterface maxError = number.getMaxError();
             //NumberInterface errorBound = fromInt(number.getClass(), 1);
             //We'll use the series \sigma_{n >= 1) ((1/3^n + 1/4^n) * 1/n)
             //In the following, a=1/3^n, b=1/4^n, c = 1/n.
@@ -301,16 +301,11 @@ public class StandardPlugin extends Plugin {
 
         @Override
         protected NumberInterface applyInternal(NumberInterface[] params) {
-            NumberInterface maxError = getMaxError(params[0]);
+            NumberInterface maxError = params[0].getMaxError();
             int n = 0;
-            if (params[0].signum() <= 0) {
+            if (params[0].signum() < 0) {
-                NumberInterface currentTerm = NaiveNumber.ONE.promoteTo(params[0].getClass()), sum = currentTerm;
+                NumberInterface[] negatedParams = {params[0].negate()};
-                while (FUNCTION_ABS.apply(currentTerm).compareTo(maxError) > 0) {
+               return fromInt(params[0].getClass(), 1).divide(applyInternal(negatedParams));
-                    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.
@@ -340,7 +335,8 @@ public class StandardPlugin extends Plugin {
         protected boolean matchesParams(NumberInterface[] params) {
             return params.length == 2
                     && !(params[0].compareTo(NaiveNumber.ZERO.promoteTo(params[0].getClass())) == 0
-                    && params[1].compareTo(NaiveNumber.ZERO.promoteTo(params[1].getClass())) == 0);
+                    && params[1].compareTo(NaiveNumber.ZERO.promoteTo(params[1].getClass())) == 0)
+                    && !(params[0].signum() == -1 && params[1].fractionalPart().compareTo(NaiveNumber.ZERO.promoteTo(params[1].getClass())) != 0);
         }
 
         @Override
@@ -349,6 +345,13 @@ public class StandardPlugin extends Plugin {
                 return NaiveNumber.ZERO.promoteTo(params[0].getClass());
             else if (params[1].compareTo(NaiveNumber.ZERO.promoteTo(params[0].getClass())) == 0)
                 return NaiveNumber.ONE.promoteTo(params[1].getClass());
+            //Detect integer bases:
+            if(params[0].fractionalPart().compareTo(fromInt(params[0].getClass(), 0)) == 0
+                    && FUNCTION_ABS.apply(params[1]).compareTo(fromInt(params[0].getClass(), Integer.MAX_VALUE)) < 0
+                    && FUNCTION_ABS.apply(params[1]).compareTo(fromInt(params[1].getClass(), 1)) >= 0){
+                NumberInterface[] newParams = {params[0], params[1].fractionalPart()};
+                return params[0].intPow(params[1].floor().intValue()).multiply(applyInternal(newParams));
+            }
             return FUNCTION_EXP.apply(FUNCTION_LN.apply(FUNCTION_ABS.apply(params[0])).multiply(params[1]));
         }
     });
@@ -468,16 +471,6 @@ public class StandardPlugin extends Plugin {
         return sum;
     }
 
-    /**
-     * Returns the maximum error based on the precision of the class of number.
-     *
-     * @param number Any instance of the NumberInterface in question (should return an appropriate precision).
-     * @return the maximum error.
-     */
-    private static NumberInterface getMaxError(NumberInterface number) {
-        return fromInt(number.getClass(), 10).intPow(-number.getMaxPrecision());
-    }
-
     /**
      * A factorial function that uses memoization for each number class; it efficiently
      * computes factorials of non-negative integers.
@@ -509,7 +502,7 @@ public class StandardPlugin extends Plugin {
      */
     private static NumberInterface sinTaylor(NumberInterface x) {
         NumberInterface power = x, multiplier = x.multiply(x).negate(), currentTerm = x, sum = x;
-        NumberInterface maxError = getMaxError(x);
+        NumberInterface maxError = x.getMaxError();
         int n = 1;
         do {
             n += 2;

src/test/java/org/nwapw/abacus/tests/CalculationTests.java

@@ -88,8 +88,8 @@ public class CalculationTests {
     public void testExp(){
         testOutput("exp0", "exp(0)", "1");
         testOutput("exp1", "exp(1)", "2.718281828459045235360287471352662497757247");
-        testOutput("exp300", "exp(300)", "19424263952412559365842088360176992193662086");
+        testOutput("exp300", "exp(300)", "1.9424263952412559365842088360176992193662086");
-        testOutput("exp300", "exp(300)", "19424263952412559365842088360176992193662086");
+        testOutput("exp(-500)", "exp((500)`)", "7.1245764067412855315491573771227552469277568");
     }
 
     @Test
@@ -99,6 +99,9 @@ public class CalculationTests {
         testOutput("2^1", "(2^1)", "2");
         testOutput("2^-1", "(2^(1)`)", "0.5");
         testOutput("2^50", "(2^50)", "112589990684262");
+        testOutput("7^(-sqrt2*17)", "(7^((sqrt(2)*17))`)", "4.81354609155297814551845300063563");
+        testEvalError("0^0", "(0^0)");
+        testEvalError("(-13)^.9999", "((13)`^0.9999)");
     }
 
 }