From 42cedf7c439921b89ddbb732905ecb6f47be0db9 Mon Sep 17 00:00:00 2001
From: Arthur Drobot <drobotarthur@gmail.com>
Date: Wed, 26 Jul 2017 11:05:12 -0700
Subject: [PATCH] Modify precision of NaiveNumber. Fix factorial to work with
 0./a.exe  Add function to get nth term of the exp Maclaurin series.

---
 src/org/nwapw/abacus/number/NaiveNumber.java    |  2 +-
 src/org/nwapw/abacus/plugin/StandardPlugin.java | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)
 mode change 100644 => 100755 src/org/nwapw/abacus/plugin/StandardPlugin.java

diff --git a/src/org/nwapw/abacus/number/NaiveNumber.java b/src/org/nwapw/abacus/number/NaiveNumber.java
index 93c501b..0a86696 100755
--- a/src/org/nwapw/abacus/number/NaiveNumber.java
+++ b/src/org/nwapw/abacus/number/NaiveNumber.java
@@ -29,7 +29,7 @@ public class NaiveNumber implements NumberInterface {
 
     @Override
     public int precision() {
-        return 4;
+        return 10;
     }
 
     @Override
diff --git a/src/org/nwapw/abacus/plugin/StandardPlugin.java b/src/org/nwapw/abacus/plugin/StandardPlugin.java
old mode 100644
new mode 100755
index 0d718c3..f7a2363
--- a/src/org/nwapw/abacus/plugin/StandardPlugin.java
+++ b/src/org/nwapw/abacus/plugin/StandardPlugin.java
@@ -80,6 +80,9 @@ public class StandardPlugin extends Plugin {
 
             @Override
             protected NumberInterface applyInternal(NumberInterface[] params) {
+                if(params[0].signum() == 0){
+                    return (new NaiveNumber(1)).promoteTo(params[0].getClass());
+                }
                 NumberInterface factorial = params[0];
                 NumberInterface multiplier = params[0];
                 //It is necessary to later prevent calls of factorial on anything but non-negative integers.
@@ -89,6 +92,18 @@ public class StandardPlugin extends Plugin {
                 return factorial;
             }
         });
+
+        System.out.println(getExpSeriesTerm(4, new NaiveNumber(3)));
+    }
+
+    /**
+     * 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
+     */
+    private NumberInterface getExpSeriesTerm(int n, NumberInterface x){
+        return x.intPow(n).divide(this.getFunction("!").apply((new NaiveNumber(n)).promoteTo(x.getClass())));
     }
 
 }