First stab at Math.lgamma

topazproject · Apr 10, 2013 · 0ece2b8 · 0ece2b8
1 parent c9b9a2f
commit 0ece2b8
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Showing 2 changed files with 10 additions and 7 deletions.
diff --git a/spec/tags/core/math/lgamma_tags.txt b/spec/tags/core/math/lgamma_tags.txt
@@ -1,9 +1,2 @@
-fails:Math.lgamma returns [Infinity, 1] when passed 0
 fails:Math.lgamma returns [Infinity, 1] when passed -1
-fails:Math.lgamma returns [log(sqrt(PI)), 1] when passed 0.5
-fails:Math.lgamma returns [log(2/3*PI, 1] when passed 6.0
-fails:Math.lgamma returns an approximate value when passed -0.5
-fails:Math.lgamma returns an approximate value when passed -1.5
-fails:Math.lgamma raises Math::DomainError when passed -Infinity
-fails:Math.lgamma returns [Infinity, 1] when passed Infinity
 fails:Math.lgamma returns [NaN, 1] when passed NaN
diff --git a/topaz/modules/math.py b/topaz/modules/math.py
@@ -101,6 +101,16 @@ def method_gamma(self, space, value):
             res = rfloat.INFINITY
         return space.newfloat(res)
 
+    @moduledef.function("lgamma", value="float")
+    def method_lgamma(self, space, value):
+        try:
+            res = rfloat.lgamma(value)
+        except (ValueError, OverflowError):
+            res = rfloat.INFINITY
+        gamma = space.float_w(space.send(self, space.newsymbol("gamma"), [space.newfloat(value)]))
+        sign = 1 if gamma >= 0 else -1 if gamma < 0 else 0
+        return space.newarray([space.newfloat(res), space.newint(sign)])
+
     @moduledef.function("hypot", value1="float", value2="float")
     def method_hypot(self, space, value1, value2):
         return space.newfloat(math.hypot(value1, value2))