From e6957eb7f488417a9b1c650eaaf3d4a9c5753339 Mon Sep 17 00:00:00 2001
From: Andi Gu <andi.gu.ca@gmail.com>
Date: Sat, 15 Oct 2016 15:51:05 -0400
Subject: [PATCH 1/3] Initial commit

---
 solution.py | 33 +++++++++++++++++++++++++++++++++
 test2.csv   |  7 +++++++
 2 files changed, 40 insertions(+)
 create mode 100644 solution.py
 create mode 100644 test2.csv

diff --git a/solution.py b/solution.py
new file mode 100644
index 0000000..ab88800
--- /dev/null
+++ b/solution.py
@@ -0,0 +1,33 @@
+def derivative(x):  # Derivative function of polynomial
+    ans = 0
+    for i in range(n):
+        degree = n - i - 1
+        ans += degree * cash_flow[i] * x ** (degree - 1)
+    return ans
+
+
+def f(x):  # Polynomial
+    ans = 0
+    for i in range(n):
+        ans += cash_flow[i] * x ** (n - i - 1)
+    ans -= market_value[-1]
+    return ans
+
+
+def solution():
+    current = 1.5
+    x = 20  # Adjust to higher value for more precision
+    for i in range(x):
+        current = current - (f(current) / derivative(current))
+    return current - 1
+
+
+data = open("test.csv").readlines()
+cash_flow = []
+market_value = []
+for line in data[1:]:
+    a, b, c = [float(i) for i in line.split(",")]
+    cash_flow.append(b)
+    market_value.append(c)
+n = len(cash_flow)
+print(solution())
diff --git a/test2.csv b/test2.csv
new file mode 100644
index 0000000..8e23876
--- /dev/null
+++ b/test2.csv
@@ -0,0 +1,7 @@
+
+0,1000,1000
+1,1500,2600
+2,0,2700
+3,0,3000
+4,0,3400
+5,0,3806
\ No newline at end of file

From 7ab9adbbd37ad0813dd1a1b8d3d785589c8bac82 Mon Sep 17 00:00:00 2001
From: Andi Gu <andi.gu.ca@gmail.com>
Date: Sat, 15 Oct 2016 15:52:42 -0400
Subject: [PATCH 2/3] Added a few comments

---
 solution.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/solution.py b/solution.py
index ab88800..5d53497 100644
--- a/solution.py
+++ b/solution.py
@@ -9,20 +9,21 @@ def derivative(x):  # Derivative function of polynomial
 def f(x):  # Polynomial
     ans = 0
     for i in range(n):
-        ans += cash_flow[i] * x ** (n - i - 1)
-    ans -= market_value[-1]
+        degree = n - i - 1
+        ans += cash_flow[i] * x ** degree
+    ans -= market_value[-1]  # Last market value
     return ans
 
 
 def solution():
     current = 1.5
-    x = 20  # Adjust to higher value for more precision
+    x = 500  # Adjust to higher value for more precision
     for i in range(x):
         current = current - (f(current) / derivative(current))
     return current - 1
 
 
-data = open("test.csv").readlines()
+data = open("test2.csv").readlines()
 cash_flow = []
 market_value = []
 for line in data[1:]:

From dd71f9b7ae209d11f402025e6afa95581785603a Mon Sep 17 00:00:00 2001
From: Andi Gu <andi.gu.ca@gmail.com>
Date: Sat, 15 Oct 2016 15:53:34 -0400
Subject: [PATCH 3/3] A few more comments!

---
 solution.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/solution.py b/solution.py
index 5d53497..962aabe 100644
--- a/solution.py
+++ b/solution.py
@@ -16,7 +16,7 @@ def f(x):  # Polynomial
 
 
 def solution():
-    current = 1.5
+    current = 1.5  # Guess for initial interest (current = 1 + x, therefore initial guess is 0.5%)
     x = 500  # Adjust to higher value for more precision
     for i in range(x):
         current = current - (f(current) / derivative(current))