math: update complex numbers

Add inverse, conjugate, and equals functions to the Complex numbers. Add
an IMAGINARY constant to represent the imaginary unit. Also, add unit
tests for different types.

test/unit/stdlib/math/math_complex.c3

@@ -0,0 +1,59 @@
+module math_tests @test;
+import math_tests::complex;
+
+def ComplexDouble = ComplexType(<double>) @local;
+def ComplexInt = ComplexType(<int>) @local;
+
+module math_tests::complex(<ElementType>) @test;
+import std::math;
+
+def ComplexType = Complex(<ElementType>);
+
+fn void! complex_mul_imaginary()
+{
+	ComplexType i = complex::IMAGINARY(<ElementType>);
+	assert(i.mul(i).equals(ComplexType{-1, 0}));
+	assert(i.mul(i).mul(i).equals(ComplexType{0, -1}));
+}
+
+fn void! complex_add()
+{
+	ComplexType a = {3, 4};
+	ComplexType b = {1, 2};
+	assert(a.add(b).equals(ComplexType{4, 6}));
+	assert(a.add_each(1).equals(ComplexType{4, 5}));
+}
+
+fn void! complex_sub()
+{
+	ComplexType a = {3, 4};
+	ComplexType b = {1, 2};
+	assert(a.sub(b).equals(ComplexType{2, 2}));
+	assert(a.sub_each(1).equals(ComplexType{2, 3}));
+}
+
+fn void! complex_scale()
+{
+	ComplexType a = {2, 1};
+	assert(a.scale(2).equals(ComplexType{4, 2}));
+}
+
+fn void! complex_conjugate()
+{
+	ComplexType a = {3, 4};
+	assert(a.conjugate().equals(ComplexType{3, -4}));
+}
+
+fn void! complex_inverse() @if(types::is_float(ElementType))
+{
+	ComplexType a = {3, 4};
+	assert(a.inverse().mul(a).equals(complex::IDENTITY(<ElementType>)));
+}
+
+fn void! complex_div() @if(types::is_float(ElementType))
+{
+	ComplexType a = {2, 5};
+	ComplexType b = {4, -1};
+	assert(a.div(b).equals(ComplexType{3.0/17.0, 22.0/17.0}));
+}
+