Merge pull request #158 from pbosetti/tests

Minor edits to test suite and Math module

src/math.c

@@ -10,6 +10,8 @@
 #define domain_error(msg) \
     mrb_raise(mrb, E_RANGE_ERROR, "Numerical argument is out of domain - " #msg);
 
+#define MATH_TOLERANCE 1E-12
+
 /* math functions not provided under Microsoft Visual C++ */
 #ifdef _MSC_VER
 #define asinh(x) log(x + sqrt(pow(x,2.0) + 1))
@@ -25,7 +27,7 @@ erfc(double x);
 ** Implementations of error functions
 ** credits to http://www.digitalmars.com/archives/cplusplus/3634.html
 */
-#define REL_ERROR 1E-12
+
 /* Implementation of Error function */
 double 
 erf(double x)
@@ -45,7 +47,7 @@ erf(double x)
     term *= xsqr/j;
     sum  += term/(2*j+1);
     ++j;
-  } while (fabs(term)/sum > REL_ERROR);
+  } while (fabs(term)/sum > MATH_TOLERANCE);
   return two_sqrtpi*sum;
 }
 
@@ -77,7 +79,7 @@ erfc(double x)
     n += 0.5;
     q1 = q2;
     q2 = b/d;
-  } while (fabs(q1-q2)/q2 > REL_ERROR);
+  } while (fabs(q1-q2)/q2 > MATH_TOLERANCE);
   return one_sqrtpi*exp(-x*x)*q2;
 }
 
@@ -610,6 +612,7 @@ mrb_init_math(mrb_state *mrb)
   struct RClass *mrb_math;
   mrb_math = mrb_define_module(mrb, "Math");
   
+  mrb_define_const(mrb, mrb_math, "TOLERANCE", mrb_float_value(MATH_TOLERANCE));
   #ifdef M_PI
       mrb_define_const(mrb, mrb_math, "PI", mrb_float_value(M_PI));
   #else

test/assert.rb

@@ -22,7 +22,7 @@ end
 # iso : The ISO reference code of the feature
 #       which will be tested by this
 #       assertion
-def assert(str = 'Assertion failed', iso = '')
+def assert(str = 'Assertion failed', iso = 'No ISO')
   begin
     if(!yield)
       $asserts.push([str, iso])

test/t/math.rb

 ##
 # Math Test
 
-MATH_TOLERANCE = 1E-12
+##
+# Performs fuzzy check for equality on methods returning floats
+# on the basis of the Math::TOLERANCE constant.
 def check(a,b)
   a = a.to_f
   b = b.to_f
   if a.finite? and b.finite?
-    (a-b).abs < MATH_TOLERANCE
+    (a-b).abs < Math::TOLERANCE
   else
     true
   end
 end
 
-
 assert('Math.sin 0') do
   check(Math.sin(0), 0)
 end
@@ -26,12 +27,13 @@ assert('Fundamental trig identities') do
   result = true
   N = 15
   N.times do |i|
-    a = Math::PI / N * i
-    s = Math.sin(a)
-    c = Math.cos(a)
-    t = Math.tan(a)
-    result &= check(s, Math.cos(Math::PI / 2 - a))
-    result &= check(t, 1 / Math.tan(Math::PI / 2 - a))
+    a  = Math::PI / N * i
+    ca = Math::PI / 2 - a
+    s  = Math.sin(a)
+    c  = Math.cos(a)
+    t  = Math.tan(a)
+    result &= check(s, Math.cos(ca))
+    result &= check(t, 1 / Math.tan(ca))
     result &= check(s ** 2 + c ** 2, 1)
     result &= check(t ** 2 + 1, (1/c) ** 2)
     result &= check((1/t) ** 2 + 1, (1/s) ** 2)
@@ -101,3 +103,16 @@ assert('Math.hypot') do
   check(Math.hypot(3, 4), 5.0)
 end
 
+assert('Math.frexp 1234') do
+  n = 1234
+  fraction, exponent = Math.frexp(n)
+  check(Math.ldexp(fraction, exponent), n)
+end
+
+assert('Math.erf 1') do
+  check(Math.erf(1), 0.842700792949715)
+end
+
+assert('Math.erfc 1') do
+  check(Math.erfc(1), 0.157299207050285)
+end