Merge pull request #805 from litmit/master

Fix xgcd for negative values
josdejong · Mar 6, 2017 · 9709a50 · 9709a50
2 parents 5d11f2e + a531715
commit 9709a50
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diff --git a/lib/function/arithmetic/xgcd.js b/lib/function/arithmetic/xgcd.js
@@ -59,7 +59,7 @@ function factory (type, config, load, typed) {
 
     while (b) {
       q = Math.floor(a / b);
-      r = a % b;
+      r = a - q*b;
 
       t = x;
       x = lastx - q * x;

diff --git a/test/function/arithmetic/xgcd.test.js b/test/function/arithmetic/xgcd.test.js
@@ -60,8 +60,7 @@ describe('xgcd', function() {
     assert.deepEqual(xgcd(65, math.bignumber(40)), [math.bignumber(5), math.bignumber(-3), math.bignumber(5)]);
   });
 
-  // FIXME: xgcd for negative values
-  it.skip('should calculate xgcd for edge cases with negative values', function () {
+  it('should calculate xgcd for edge cases with negative values', function () {
     assert.deepEqual([1, -2, 1], xgcd(2, 5));
     assert.deepEqual([1, -2, -1], xgcd(2, -5));
     assert.deepEqual([1, 2, 1], xgcd(-2, 5));