Changeset 8054

Timestamp:

12/03/05 07:06:08 (3 years ago)

Author:

luqui

svk:copy_cache_prev:

10519

Message:

Added tests about infinity, and "fixed" op2Exp to make them pass. They should
be checked for correctness.

Files:

• src/Pugs/Prim/Numeric.hs (modified) (2 diffs)
• t/operators/arith.t (modified) (3 diffs)

src/Pugs/Prim/Numeric.hs

@@ -61 +61 @@
             if isDigit . head $ show (num1 :: VNum)
                 then op2Rat ((^^) :: VRat -> VInt -> VRat) x y
-                else op2Num ((**) :: VNum -> VNum -> VNum) x y
-        _ -> op2Num ((**) :: VNum -> VNum -> VNum) x y
+                else op2Num numExp x y
+        _ -> op2Num numExp x y
+    where
+    numExp :: VNum -> VNum -> VNum
+    -- Perl 6 differs from Haskell in the floating point spec wrt Infinity and NaN
+    numExp x y 
+        | x == 1/0 && y == 0                           = 0/0
+        | x == 0  && y < 0                             = 0/0
+        | y == 1/0 && (x == 1 || x <= -1)              = 0/0 
+        | y == -1/0 && (x == 1 || (x >= -1 && x <= 0)) = 0/0 
+        | otherwise                                    = x ** y
 
 op2Divide :: Val -> Val -> Eval Val
@@ -77 +86 @@
     = op2Num (/) x y
     where
-    err = fail "Illegal division by zero"
+    err = fail "Illegal division by zero"  -- XXX why not NaN?
 
 op2Modulus :: Val -> Val -> Eval Val

t/operators/arith.t

@@ -4 +4 @@
 use Test;
 
-plan 185;
+plan 196;
 
 my $five = abs(-5);
@@ -311 +311 @@
 is Inf/Inf, NaN;
 is Inf*Inf/Inf, NaN;
-is Inf**0, 1;
 is 0**Inf, 0;
 
@@ -324 +323 @@
 is 0.9**Inf, 0,   "0.9**Inf converges towards 0";
 is 1.1**Inf, Inf, "1.1**Inf diverges towards Inf";
-is 1**Inf, 1 , :todo("1**Inf == 1");
+# this next one is arguable
+is 1**Inf, NaN,   "1**Inf depends on the functions in the limit (unless 1 is considered an int)";
+# but this next one isn't
+is 1.0**Inf, NaN, "1.0**Inf depends on the functions in the limit";
+is (-1)**Inf, NaN, "(-1)**Inf is indeterminate for the same reason";
+is (-1.1)**Inf, NaN, "(-2)**Inf is indeterminate between -Inf and Inf";
+is (-0.9)**Inf, 0, "(-0.9)**Inf oscillates but always converges to 0";
+
+is 0.9**(-Inf), Inf, "0.9**-Inf diverges towards Inf";
+is 1.1**(-Inf), 0,   "1.1**-Inf converges to 0";
+is 1**(-Inf), NaN, "1**Inf depends on the functions in the limit";
+is 1.0**(-Inf), NaN, "1.0**Inf depends on the functions in the limit";
+is (-1)**(-Inf), NaN, "(-1)**-Inf is indeterminate";
+is (-1.1)**(-Inf), 0, "(-1.1)**-Inf converges to 0";
+is (-0.9)**(-Inf), NaN, "(0.9)**-Inf oscillates and diverges";
+
+is Inf**0, NaN;
 
 #fail("1**Inf is platform-specific -- it's 1 on OSX and NaN elsewhere", :todo);