com.livecode.math: Check function domain errors portably.

peter-b · peter-b · commit f58c8b752405 · 2015-03-13T16:13:30.000Z
Only glibc sets EDOM for mathematical function domain errors.  All
platforms return NaN, however.  Check for domain errors by checking
for NaN result when none of the function's inputs were NaN.
diff --git a/libscript/src/module-math.cpp b/libscript/src/module-math.cpp
@@ -19,6 +19,7 @@
 #include <foundation-system.h>
 
 #include <float.h>
+#include <fenv.h>
 #include <errno.h>
 
 // Older versions of MSVC don't supply "trunc"
@@ -32,15 +33,32 @@ MCTypeInfoRef kMCMathDomainErrorTypeInfo;
 
 ////////////////////////////////////////////////////////////////
 
+static inline bool
+__MCMathPropagateNanUnary (double p_in, double p_out)
+{
+    if (isnan (p_out) && !isnan (p_in))
+        return false;
+    return true;
+}
+
+static inline bool
+__MCMathPropagateNanBinary (double p_left, double p_right, double p_out)
+{
+    if (isnan (p_out) && (!(isnan (p_left) || isnan (p_right))))
+        return false;
+    return true;
+}
+
+////////////////////////////////////////////////////////////////
+
 extern "C" MC_DLLEXPORT void MCMathEvalRealToPowerOfReal(double p_left, double p_right, double& r_output)
 {
-	errno = 0;
     r_output = pow(p_left, p_right);
 
-	if (errno == EDOM)
-	{
-		MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
-	}
+    if (__MCMathPropagateNanBinary (p_left, p_right, r_output))
+        return;
+
+    MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
 }
 
 extern "C" MC_DLLEXPORT void MCMathEvalNumberToPowerOfNumber(MCNumberRef p_left, MCNumberRef p_right, MCNumberRef& r_output)
@@ -58,13 +76,12 @@ extern "C" MC_DLLEXPORT void MCMathEvalNumberToPowerOfNumber(MCNumberRef p_left,
 
 extern "C" MC_DLLEXPORT void MCMathEvalBase10LogReal(double p_operand, double& r_output)
 {
-	errno = 0;
     r_output = log10(p_operand);
 
-	if (errno == EDOM)
-	{
-		MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
-	}
+    if (__MCMathPropagateNanUnary (p_operand, r_output))
+        return;
+
+    MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
 }
 
 extern "C" MC_DLLEXPORT void MCMathEvalBase10LogNumber(MCNumberRef p_operand, MCNumberRef& r_output)
@@ -81,13 +98,12 @@ extern "C" MC_DLLEXPORT void MCMathEvalBase10LogNumber(MCNumberRef p_operand, MC
 
 extern "C" MC_DLLEXPORT void MCMathEvalNaturalLogReal(double p_operand, double& r_output)
 {
-	errno = 0;
     r_output = log(p_operand);
 
-	if (errno == EDOM)
-	{
-		MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
-	}
+    if (__MCMathPropagateNanUnary (p_operand, r_output))
+        return;
+
+    MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
 }
 
 extern "C" MC_DLLEXPORT void MCMathEvalNaturalLogNumber(MCNumberRef p_operand, MCNumberRef& r_output)
@@ -172,13 +188,12 @@ extern "C" MC_DLLEXPORT void MCMathEvalTanNumber(MCNumberRef p_operand, MCNumber
 
 extern "C" MC_DLLEXPORT void MCMathEvalAsinReal(double p_operand, double& r_output)
 {
-	errno = 0;
     r_output = asin(p_operand);
 
-	if (errno == EDOM)
-	{
-		MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
-	}
+    if (__MCMathPropagateNanUnary (p_operand, r_output))
+        return;
+
+    MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
 }
 
 extern "C" MC_DLLEXPORT void MCMathEvalAsinNumber(MCNumberRef p_operand, MCNumberRef& r_output)
@@ -195,13 +210,12 @@ extern "C" MC_DLLEXPORT void MCMathEvalAsinNumber(MCNumberRef p_operand, MCNumbe
 
 extern "C" MC_DLLEXPORT void MCMathEvalAcosReal(double p_operand, double& r_output)
 {
-	errno = 0;
     r_output = acos(p_operand);
 
-	if (errno == EDOM)
-	{
-		MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
-	}
+    if (__MCMathPropagateNanUnary (p_operand, r_output))
+        return;
+
+    MCErrorCreateAndThrow (kMCMathDomainErrorTypeInfo, nil);
 }
 
 extern "C" MC_DLLEXPORT void MCMathEvalAcosNumber(MCNumberRef p_operand, MCNumberRef& r_output)
