mat: Add CDense type and basic methods (#846)

* mat: Add CDense type and basic methods

Updates #738.

mat/cdense_test.go

@@ -0,0 +1,48 @@
+// Copyright ©2019 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package mat
+
+import "testing"
+
+func TestCDenseNewAtSet(t *testing.T) {
+	for cas, test := range []struct {
+		a          []complex128
+		rows, cols int
+	}{
+		{
+			a: []complex128{0, 0, 0,
+				0, 0, 0,
+				0, 0, 0},
+			rows: 3,
+			cols: 3,
+		},
+	} {
+		aCopy := make([]complex128, len(test.a))
+		copy(aCopy, test.a)
+		mZero := NewCDense(test.rows, test.cols, nil)
+		rows, cols := mZero.Dims()
+		if rows != test.rows {
+			t.Errorf("unexpected number of rows for test %d: got: %d want: %d", cas, rows, test.rows)
+		}
+		if cols != test.cols {
+			t.Errorf("unexpected number of cols for test %d: got: %d want: %d", cas, cols, test.cols)
+		}
+		m := NewCDense(test.rows, test.cols, aCopy)
+		for i := 0; i < test.rows; i++ {
+			for j := 0; j < test.cols; j++ {
+				v := m.At(i, j)
+				idx := i*test.rows + j
+				if v != test.a[idx] {
+					t.Errorf("unexpected get value for test %d at i=%d, j=%d: got: %v, want: %v", cas, i, j, v, test.a[idx])
+				}
+				add := complex(float64(i+1), float64(j+1))
+				m.Set(i, j, v+add)
+				if m.At(i, j) != test.a[idx]+add {
+					t.Errorf("unexpected set value for test %d at i=%d, j=%d: got: %v, want: %v", cas, i, j, v, test.a[idx]+add)
+				}
+			}
+		}
+	}
+}