add - npm Package Compare versions

Comparing version 1.0.0 to 2.0.0

index.js

@@ -0,6 +1,138 @@
+    // The minimum machine rounding error
+var Epsilon = Math.pow(2, -53)
+  , EpsilonReciprocal = (1 / Epsilon)
+    /// The smallest positive number that can be represented
+  , Eta = Math.pow(2, -1074)
+    // limitB is a constant used in the transform function
+  , limitB = 0.5 * EpsilonReciprocal * Eta
 
-module.exports = add
+/**
+* S. M. RUMP, T. OGITA AND S. OISHI
+* http://www.ti3.tu-harburg.de/paper/rump/RuOgOi07I.pdf
+*/
 
-function add(a, b) {
-	return a + b
+// Page 8
+// x is result, y is error
+// third is so the array is allocated for 4 spaces
+// it speeds up transform
+function fastTwoSum(a, b) {
+  var x = a + b
+    , q = x - a
+    , y = b - q
+
+  return [x, y, null]
 }
+
+// Page 12
+// p = q + p'
+// sigma is a power of 2 greater than or equal to |p|
+function extractScalar(sigma, p) {
+  var q = (sigma + p) - sigma
+    , pPrime = p - q
+
+  return [q, pPrime]
+}
+
+// Page 12
+function extractVector(sigma, p) {
+  var tau = 0.0
+    , extracted
+    , i = 0
+    , ii = p.length
+    , pPrime = new Array(ii)
+
+  for(; i<ii; ++i) {
+    extracted = extractScalar(sigma, p[i])
+    pPrime[i] = extracted[1]
+    tau += extracted[0]
+  }
+
+  return [tau, pPrime]
+}
+
+// Finds the immediate power of 2 that is larger than p
+//// in a fast way
+function nextPowerTwo (p) {
+  var q = EpsilonReciprocal * p
+    , L = Math.abs((q + p) - q)
+
+  if(L === 0)
+    return Math.abs(p)
+
+  return L
+}
+
+// Helper, gets the maximum of the absolute values of an array
+function maxAbs(arr) {
+  var i = 0
+    , ii = arr.length
+    , best = -1
+
+  for(; i<ii; ++i) {
+    if(Math.abs(arr[i]) > best) {
+      best = arr[i]
+    }
+  }
+
+  return best
+}
+
+function transform (p) {
+  var mu = maxAbs(p)
+    , M
+    , sigmaPrime
+    , tPrime
+    , t
+    , tau
+    , sigma
+    , extracted
+    , res
+
+      // Not part of the original paper, here for optimization
+    , temp
+    , bigPow
+    , limitA
+
+  if(mu === 0) {
+    return [0, 0, p, 0]
+  }
+
+  M = nextPowerTwo(p.length + 2)
+  bigPow = Math.pow(2, 2 * M)
+  sigmaPrime = Math.pow(2, M) * nextPowerTwo(mu)
+  tPrime = 0
+
+  do {
+    t = tPrime
+    sigma = sigmaPrime
+    extracted = extractVector(sigma, p)
+    tau = extracted[0]
+    tPrime = t + tau
+    p = extracted[1]
+
+    if(tPrime === 0) {
+      return transform(p)
+    }
+
+    temp = Epsilon * sigma
+    sigmaPrime = Math.pow(2, M) * temp
+    limitA = bigPow * temp
+  }
+  while( Math.abs(tPrime) < limitA && sigma > limitB )
+
+  // res already allocated for 4
+  res = fastTwoSum(t, tau)
+  res[2] = p
+
+  return res
+}
+
+function accSum(p) {
+  var tfmd = transform(p)
+
+  return tfmd[0] + (tfmd[1] + tfmd[2].reduce(function (a,b){return a+b}))
+}
+
+module.exports = accSum
+module.exports.fastTwoSum = fastTwoSum
+module.exports.nextPowerTwo = nextPowerTwo

package.json

 {
   "name": "add",
-  "version": "1.0.0",
-  "description": "Add two numbers",
-  "keywords": [],
-  "author": "Raynos <[e-mail]>",
-  "repository": "git://github.com/Raynos/add.git",
-  "main": "index",
-  "homepage": "https://github.com/Raynos/add",
-  "contributors": [{
-    "name": "Raynos"
-  }],
-  "bugs": {
-    "url": "https://github.com/Raynos/add/issues",
-    "email": "[e-mail]"
+  "version": "2.0.0",
+  "description": "A numerically stable algorithm to add numbers accurately",
+  "main": "index.js",
+  "scripts": {
+    "test": "node test.js"
   },
-  "dependencies": {},
-  "devDependencies": {
-    "tape": "~2.1.0"
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/ben-ng/add.git"
   },
-  "licenses": [{
-    "type": "MIT",
-    "url": "http://github.com/Raynos/add/raw/master/LICENSE"
-  }],
-  "scripts": {
-    "test": "node ./test/index.js"
+  "keywords": [
+    "numerically",
+    "stable",
+    "error",
+    "propagation",
+    "summation",
+    "accumulate",
+    "addition",
+    "analysis"
+  ],
+  "author": "Ben Ng <[e-mail]>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/ben-ng/add/issues"
   },
-  "testling": {
-    "files": "test/index.js",
-    "browsers": [
-      "ie/8..latest",
-      "firefox/16..latest",
-      "firefox/nightly",
-      "chrome/22..latest",
-      "chrome/canary",
-      "opera/12..latest",
-      "opera/next",
-      "safari/5.1..latest",
-      "ipad/6.0..latest",
-      "iphone/6.0..latest",
-      "android-browser/4.2..latest"
-    ]
-  }
+  "homepage": "https://github.com/ben-ng/add"
 }

New alerts

License Policy Violation

License

This package is not allowed per your license policy. Review the package's license to ensure compliance.

Found 1 instance in 1 package

Major refactor

Supply chain risk

Package has recently undergone a major refactor. It may be unstable or indicate significant internal changes. Use caution when updating to versions that include significant changes.

Found 1 instance in 1 package

New author

Supply chain risk

A new npm collaborator published a version of the package for the first time. New collaborators are usually benign additions to a project, but do indicate a change to the security surface area of a package.

Found 1 instance in 1 package

Fixed alerts

License Policy Violation

License

This package is not allowed per your license policy. Review the package's license to ensure compliance.

Found 1 instance in 1 package

No repository

Supply chain risk

Package does not have a linked source code repository. Without this field, a package will have no reference to the location of the source code use to generate the package.

Found 1 instance in 1 package

Improved metrics

Total package byte prevSize

5956

increased by103.9%

Dev dependency count

0

decreased by-100%

Lines of code

131

increased by835.71%

Number of lines in readme file

44

increased by100%

Number of low supply chain risk alerts

0

decreased by-100%

Worsened metrics

Number of package files

5

decreased by-37.5%

Number of medium supply chain risk alerts

2

increased byInfinity%

No dependency changes