From dc3663850fa17c58f7699e9b14a41c5517b2f3e2 Mon Sep 17 00:00:00 2001
From: Will Charczuk <will@blendlabs.com>
Date: Mon, 17 Apr 2017 17:05:55 -0700
Subject: [PATCH] test coverage

---
 matrix/matrix.go      |  4 ++--
 matrix/matrix_test.go | 12 ++++++++++++
 matrix/util.go        |  5 +++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/matrix/matrix.go b/matrix/matrix.go
index fc02e56..c307cd5 100644
--- a/matrix/matrix.go
+++ b/matrix/matrix.go
@@ -3,7 +3,6 @@ package matrix
 import (
 	"bytes"
 	"errors"
-	"fmt"
 	"math"
 )
 
@@ -239,6 +238,7 @@ func (m *Matrix) L() *Matrix {
 }
 
 // U returns the matrix with zeros above the diagonal.
+// Does not include the diagonal.
 func (m *Matrix) U() *Matrix {
 	m2 := New(m.rows, m.cols)
 	for row := 0; row < m.rows; row++ {
@@ -254,7 +254,7 @@ func (m *Matrix) String() string {
 	buffer := bytes.NewBuffer(nil)
 	for row := 0; row < m.rows; row++ {
 		for col := 0; col < m.cols; col++ {
-			buffer.WriteString(fmt.Sprintf("%f", m.Get(row, col)))
+			buffer.WriteString(f64s(m.Get(row, col)))
 			buffer.WriteRune(' ')
 		}
 		buffer.WriteRune('\n')
diff --git a/matrix/matrix_test.go b/matrix/matrix_test.go
index ad00a7c..d9a8dc3 100644
--- a/matrix/matrix_test.go
+++ b/matrix/matrix_test.go
@@ -316,3 +316,15 @@ func TestMatrixU(t *testing.T) {
 	u := m.U()
 	assert.True(u.Equals(New(3, 3, 0, 0, 0, 4, 0, 0, 7, 8, 0)))
 }
+
+func TestMatrixString(t *testing.T) {
+	assert := assert.New(t)
+
+	m := NewFromArrays([][]float64{
+		{1, 2, 3},
+		{4, 5, 6},
+		{7, 8, 9},
+	})
+
+	assert.Equal("1 2 3 \n4 5 6 \n7 8 9 \n", m.String())
+}
diff --git a/matrix/util.go b/matrix/util.go
index be851f2..094d93a 100644
--- a/matrix/util.go
+++ b/matrix/util.go
@@ -2,6 +2,7 @@ package matrix
 
 import (
 	"math"
+	"strconv"
 )
 
 func minInt(values ...int) int {
@@ -25,3 +26,7 @@ func maxInt(values ...int) int {
 	}
 	return max
 }
+
+func f64s(v float64) string {
+	return strconv.FormatFloat(v, 'f', -1, 64)
+}