mat: add NonZeroDoer interfaces and implementations

Also clean up some documentation and missing type checks related to
tests for NonZeroDoers.

mat/matrix_test.go

@@ -521,3 +521,94 @@ func TestTrace(t *testing.T) {
 	}
 	testOneInputFunc(t, "Trace", f, denseComparison, sameAnswerFloat, isAnyType, isSquare)
 }
+
+func TestDoer(t *testing.T) {
+	type MatrixDoer interface {
+		Matrix
+		NonZeroDoer
+		RowNonZeroDoer
+		ColNonZeroDoer
+	}
+	ones := func(n int) []float64 {
+		data := make([]float64, n)
+		for i := range data {
+			data[i] = 1
+		}
+		return data
+	}
+	for i, m := range []MatrixDoer{
+		NewTriDense(3, Lower, ones(3*3)),
+		NewTriDense(3, Upper, ones(3*3)),
+		NewBandDense(6, 6, 1, 1, ones(3*6)),
+		NewBandDense(6, 10, 1, 1, ones(3*6)),
+		NewBandDense(10, 6, 1, 1, ones(7*3)),
+		NewSymBandDense(3, 0, ones(3)),
+		NewSymBandDense(3, 1, ones(3*(1+1))),
+		NewSymBandDense(6, 1, ones(6*(1+1))),
+		NewSymBandDense(6, 2, ones(6*(2+1))),
+	} {
+		r, c := m.Dims()
+
+		want := Sum(m)
+
+		// got and fn sum the accessed elements in
+		// the Doer that is being operated on.
+		// fn also tests that the accessed elements
+		// are within the writable areas of the
+		// matrix to check that only valid elements
+		// are operated on.
+		var got float64
+		fn := func(i, j int, v float64) {
+			got += v
+			switch m := m.(type) {
+			case MutableTriangular:
+				m.SetTri(i, j, v)
+			case MutableBanded:
+				m.SetBand(i, j, v)
+			case MutableSymBanded:
+				m.SetSymBand(i, j, v)
+			default:
+				panic("bad test: need mutable type")
+			}
+		}
+
+		panicked, message := panics(func() { m.DoNonZero(fn) })
+		if panicked {
+			t.Errorf("unexpected panic for Doer test %d: %q", i, message)
+			continue
+		}
+		if got != want {
+			t.Errorf("unexpected Doer sum: got:%f want:%f", got, want)
+		}
+
+		// Reset got for testing with DoRowNonZero.
+		got = 0
+		panicked, message = panics(func() {
+			for i := 0; i < r; i++ {
+				m.DoRowNonZero(i, fn)
+			}
+		})
+		if panicked {
+			t.Errorf("unexpected panic for RowDoer test %d: %q", i, message)
+			continue
+		}
+		if got != want {
+			t.Errorf("unexpected RowDoer sum: got:%f want:%f", got, want)
+		}
+
+		// Reset got for testing with DoColNonZero.
+		got = 0
+		panicked, message = panics(func() {
+			for j := 0; j < c; j++ {
+				m.DoColNonZero(j, fn)
+			}
+		})
+		if panicked {
+			t.Errorf("unexpected panic for ColDoer test %d: %q", i, message)
+			continue
+		}
+		if got != want {
+			t.Errorf("unexpected ColDoer sum: got:%f want:%f", got, want)
+		}
+	}
+}