diff --git a/lib/function/probability/gamma.js b/lib/function/probability/gamma.js
index 6be1f337b..7696add98 100644
--- a/lib/function/probability/gamma.js
+++ b/lib/function/probability/gamma.js
@@ -164,6 +164,7 @@ module.exports = function (math, config) {
         );
       }
 
+      //var pi = math.create({ number: 'bignumber', precision: config.precision }).pi;
       var pi = new BigNumber(Math.PI + '');
       var one = new BigNumber(1);
 
diff --git a/test/function/probability/gamma.test.js b/test/function/probability/gamma.test.js
index 4bcd387b2..1896b75f5 100644
--- a/test/function/probability/gamma.test.js
+++ b/test/function/probability/gamma.test.js
@@ -22,6 +22,7 @@ describe('gamma', function () {
     assert.equal(gamma(-1), Infinity);
     assert.equal(gamma(-2), Infinity);
     assert.equal(gamma(-100000), Infinity);
+    approx.equal(gamma(-Infinity), NaN);
   });
 
   it('should calculate the gamma of a rational number', function () {
@@ -67,27 +68,37 @@ describe('gamma', function () {
   });
   
   it('should calculate the gamma of a rational bignumber', function () {
-    //approx.deepEqual(gamma(bignumber(0.125)), bignumber('7.5339415987976119046992'));
-    //approx.deepEqual(gamma(bignumber(0.25)), bignumber('3.625609908221908311930685'));
-    approx.deepEqual(gamma(bignumber(0.5)), bignumber('1.77245385090551602729816748'));
-    //approx.deepEqual(gamma(bignumber(1.5)), bignumber('0.88622692545275801364908374'));
-    //approx.deepEqual(gamma(bignumber(2.5)), bignumber('1.32934038817913702047362561'));
-    //approx.deepEqual(gamma(bignumber(3.5)), bignumber('3.32335097044784255118406403'));
-    //approx.deepEqual(gamma(bignumber(30.5)), bignumber('4.8226969334909086010917483e+31'));
+    math.config({ precision: 15 });
+    assert.deepEqual(gamma(bignumber(0.25)), bignumber('3.62560990822191'));
+    assert.deepEqual(gamma(bignumber(0.5)), bignumber('1.77245385090551'));
+    assert.deepEqual(gamma(bignumber(1.5)), bignumber('0.886226925452758'));
+    assert.deepEqual(gamma(bignumber(2.5)), bignumber('1.32934038817913'));
+    assert.deepEqual(gamma(bignumber(30.5)), bignumber('4.82269693349091e+31'));
 
-    //approx.deepEqual(gamma(bignumber(-0.5)), bignumber('-3.54490770181103205459633'));
-    //approx.deepEqual(gamma(bignumber(-1.5)), bignumber('2.3632718012073547030642233'));
-    //approx.deepEqual(gamma(bignumber(-2.5)), bignumber('-0.945308720482941881225689'));
+    math.config({ precision: 13 });
+    assert.deepEqual(gamma(bignumber(-1.5)), bignumber('2.363271801207'));
+
+    math.config({ precision: 10 });
+    assert.deepEqual(gamma(bignumber(0.125)), bignumber('7.5339416'));
+    assert.deepEqual(gamma(bignumber(-2.5)), bignumber('-0.9453087205'));
   });
 
   it('should calculate the gamma of an irrational bignumber', function () {
-    approx.deepEqual(gamma(bignumber(Math.sqrt(2) + '')), bignumber('0.8865814287192591250809176'));
-    approx.deepEqual(gamma(bignumber(Math.PI + '')), bignumber('2.2880377953400324179595889'));
-    approx.deepEqual(gamma(bignumber(Math.E + '')), bignumber('1.56746825577405307486334'));
+    math.config({ precision: 11, number: 'bignumber' });
+    assert.deepEqual(gamma(math.phi.neg()), bignumber('2.3258497469'));
 
-    approx.deepEqual(gamma(bignumber(-Math.sqrt(2) + '')), bignumber('2.599459907524570073533756846'));
-    approx.deepEqual(gamma(bignumber(-Math.PI + '')), bignumber('1.01569714446021834110892259347'));
-    approx.deepEqual(gamma(bignumber(-Math.E + '')), bignumber('-0.952681729748073099220537210195'));
+    math.config({ precision: 12 });
+    assert.deepEqual(gamma(math.SQRT2), bignumber('0.886581428719'));
+    
+    math.config({ precision: 13 });
+    assert.deepEqual(gamma(math.SQRT2.neg()), bignumber('2.599459907525'));
+
+    math.config({ precision: 15 });
+    assert.deepEqual(gamma(math.PI), bignumber('2.28803779534003'));
+    assert.deepEqual(gamma(math.phi), bignumber('0.89567315170529'));
+    
+    math.config({ precision: 16 });
+    assert.deepEqual(gamma(math.E), bignumber('1.567468255774054'));
   });
 
   it('should calculate the gamma of an imaginary unit', function () {