From 1ceccefe7780f52a6df2f0ece2be9655821a1c58 Mon Sep 17 00:00:00 2001
From: Mitchell Skaggs <skaggsm333@gmail.com>
Date: Sat, 16 Jan 2021 09:39:07 -0600
Subject: [PATCH 1/4] Update axios to fix CVE-2020-28168

---
 package.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package.json b/package.json
index 0cb50dc167e6e..eda0a52c70ead 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,7 @@
     "@actions/github": "^4.0.0",
     "@testing-library/dom": "^7.20.0",
     "@testing-library/jest-dom": "^5.11.0",
-    "axios": "^0.19.2",
+    "axios": "^0.21.1",
     "axios-mock-adapter": "^1.18.1",
     "css-to-object": "^1.1.0",
     "husky": "^4.2.5",

From da5b487992d7258391280841ceb9f99e5f96386d Mon Sep 17 00:00:00 2001
From: Mitchell Skaggs <skaggsm333@gmail.com>
Date: Sat, 16 Jan 2021 09:55:03 -0600
Subject: [PATCH 2/4] Use exact normal CDF function for rank calculation

Uses Math.js for erf function
---
 package.json                |  3 ++-
 src/calculateRank.js        | 24 +++++++-----------------
 tests/calculateRank.test.js |  2 +-
 3 files changed, 10 insertions(+), 19 deletions(-)

diff --git a/package.json b/package.json
index eda0a52c70ead..52dbeea873377 100644
--- a/package.json
+++ b/package.json
@@ -28,7 +28,8 @@
     "emoji-name-map": "^1.2.8",
     "github-username-regex": "^1.0.0",
     "prettier": "^2.1.2",
-    "word-wrap": "^1.2.3"
+    "word-wrap": "^1.2.3",
+    "mathjs": "^9.0.0"
   },
   "husky": {
     "hooks": {
diff --git a/src/calculateRank.js b/src/calculateRank.js
index 76909d09547cd..f821b41bd3da2 100644
--- a/src/calculateRank.js
+++ b/src/calculateRank.js
@@ -1,19 +1,9 @@
-// https://stackoverflow.com/a/5263759/10629172
+const { erf } = require("mathjs");
+const sqrt2 = Math.sqrt(2);
 function normalcdf(mean, sigma, to) {
-  var z = (to - mean) / Math.sqrt(2 * sigma * sigma);
-  var t = 1 / (1 + 0.3275911 * Math.abs(z));
-  var a1 = 0.254829592;
-  var a2 = -0.284496736;
-  var a3 = 1.421413741;
-  var a4 = -1.453152027;
-  var a5 = 1.061405429;
-  var erf =
-    1 - ((((a5 * t + a4) * t + a3) * t + a2) * t + a1) * t * Math.exp(-z * z);
-  var sign = 1;
-  if (z < 0) {
-    sign = -1;
-  }
-  return (1 / 2) * (1 + sign * erf);
+  const z = (to - mean) / (sigma * sqrt2);
+  const erfZ = erf(z);
+  return 0.5 + 0.5 * erfZ;
 }
 
 function calculateRank({
@@ -57,8 +47,8 @@ function calculateRank({
     issues * ISSUES_OFFSET +
     stargazers * STARS_OFFSET +
     prs * PRS_OFFSET +
-    followers * FOLLOWERS_OFFSET + 
-    totalRepos * REPO_OFFSET 
+    followers * FOLLOWERS_OFFSET +
+    totalRepos * REPO_OFFSET
   ) / 100;
 
   const normalizedScore = normalcdf(score, TOTAL_VALUES, ALL_OFFSETS) * 100;
diff --git a/tests/calculateRank.test.js b/tests/calculateRank.test.js
index 4b9fd072b4aa4..7df50b4534999 100644
--- a/tests/calculateRank.test.js
+++ b/tests/calculateRank.test.js
@@ -13,6 +13,6 @@ describe("Test calculateRank", () => {
         prs: 300,
         issues: 200,
       }),
-    ).toStrictEqual({ level: "A+", score: 49.16605417270399 });
+    ).toStrictEqual({ level: "A+", score: 49.16605835034125 });
   });
 });

From dacfa85cc4c547b0c755d64157e59b5c5d71be8c Mon Sep 17 00:00:00 2001
From: Mitchell Skaggs <skaggsm333@gmail.com>
Date: Sat, 16 Jan 2021 10:03:42 -0600
Subject: [PATCH 3/4] Document source of normal CDF

---
 src/calculateRank.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/calculateRank.js b/src/calculateRank.js
index f821b41bd3da2..e5707b0a26945 100644
--- a/src/calculateRank.js
+++ b/src/calculateRank.js
@@ -1,5 +1,6 @@
 const { erf } = require("mathjs");
 const sqrt2 = Math.sqrt(2);
+// https://en.wikipedia.org/wiki/Normal_distribution#Cumulative_distribution_function
 function normalcdf(mean, sigma, to) {
   const z = (to - mean) / (sigma * sqrt2);
   const erfZ = erf(z);

From c36810ad615ee8ddf81b2be6bb65b554251a7c77 Mon Sep 17 00:00:00 2001
From: Mitchell Skaggs <skaggsm333@gmail.com>
Date: Sun, 17 Jan 2021 08:09:13 -0600
Subject: [PATCH 4/4] Clean up implementation based on Wolfram MathWorld
 directly

---
 src/calculateRank.js | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/calculateRank.js b/src/calculateRank.js
index e5707b0a26945..cf42f9c56b0bb 100644
--- a/src/calculateRank.js
+++ b/src/calculateRank.js
@@ -1,10 +1,9 @@
 const { erf } = require("mathjs");
-const sqrt2 = Math.sqrt(2);
-// https://en.wikipedia.org/wiki/Normal_distribution#Cumulative_distribution_function
+const invSqrt2 = 1 / Math.sqrt(2);
+// https://mathworld.wolfram.com/NormalDistribution.html
 function normalcdf(mean, sigma, to) {
-  const z = (to - mean) / (sigma * sqrt2);
-  const erfZ = erf(z);
-  return 0.5 + 0.5 * erfZ;
+  const a = (invSqrt2 * (to - mean)) / sigma;
+  return (1 + erf(a)) / 2;
 }
 
 function calculateRank({