complex.c: multiply as rotation

* complex.c (nucomp_mul): calculate as rotation in complex plane
  if matrix calculation resulted in NaN.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49723 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Tue Feb 24 22:58:48 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* complex.c (nucomp_mul): calculate as rotation in complex plane
+	  if matrix calculation resulted in NaN.
+
 Tue Feb 24 21:45:39 2015  Kazuki Tanaka  <mail@tanakakazuki.com>
 
 	* test/ruby/test_math.rb(test_cbrt): Add an assertion for Math.cbrt(1.0/0)

complex.c

@@ -17,6 +17,9 @@
 
 VALUE rb_cComplex;
 
+static VALUE nucomp_abs(VALUE self);
+static VALUE nucomp_arg(VALUE self);
+
 static ID id_abs, id_arg, id_convert,
     id_denominator, id_eqeq_p, id_expt, id_fdiv,
     id_negate, id_numerator, id_quo,
@@ -720,6 +723,38 @@ nucomp_mul(VALUE self, VALUE other)
 	imag = f_add(f_mul(adat->real, bdat->imag),
 		     f_mul(adat->imag, bdat->real));
 
+	if ((RB_FLOAT_TYPE_P(real) && isnan(RFLOAT_VALUE(real))) ||
+	    (RB_FLOAT_TYPE_P(imag) && isnan(RFLOAT_VALUE(imag)))) {
+	    VALUE abs = f_mul(nucomp_abs(self), nucomp_abs(other));
+	    VALUE arg = f_add(nucomp_arg(self), nucomp_arg(other));
+	    if (f_zero_p(arg)) {
+		real = abs;
+		imag = INT2FIX(0);
+	    }
+	    else if (RB_FLOAT_TYPE_P(arg)) {
+		double a = RFLOAT_VALUE(arg);
+		if (a == M_PI) {
+		    real = f_negate(abs);
+		    imag = INT2FIX(0);
+		}
+		else if (a == M_PI/2) {
+		    imag = abs;
+		    real = INT2FIX(0);
+		}
+		else if (a == M_PI*3/2) {
+		    imag = f_negate(abs);
+		    real = INT2FIX(0);
+		}
+		else {
+		    goto polar;
+		}
+	    }
+	    else {
+	      polar:
+		return f_complex_polar(CLASS_OF(self), abs, arg);
+	    }
+	}
+
 	return f_complex_new2(CLASS_OF(self), real, imag);
     }
     if (k_numeric_p(other) && f_real_p(other)) {

test/ruby/test_complex.rb

@@ -289,6 +289,13 @@ class Complex_Test < Test::Unit::TestCase
 
     assert_equal(Complex(Rational(2,1),Rational(4)), c * Rational(2))
     assert_equal(Complex(Rational(2,3),Rational(4,3)), c * Rational(2,3))
+
+    c = Complex(Float::INFINITY, 0)
+    assert_equal(Complex(Float::INFINITY, 0), c * Complex(1, 0))
+    assert_equal(Complex(0, Float::INFINITY), c * Complex(0, 1))
+    c = Complex(0, Float::INFINITY)
+    assert_equal(Complex(0, Float::INFINITY), c * Complex(1, 0))
+    assert_equal(Complex(-Float::INFINITY, 0), c * Complex(0, 1))
   end
 
   def test_div