allow 'zero y-range delta' (#72)

chart.go

@@ -317,9 +317,6 @@ func (c Chart) checkRanges(xr, yr, yra Range) error {
 	if math.IsNaN(yDelta) {
 		return errors.New("nan y-range delta")
 	}
-	if yDelta == 0 {
-		return errors.New("zero y-range delta")
-	}
 
 	if c.hasSecondarySeries() {
 		yraDelta := yra.GetDelta()
@@ -329,9 +326,6 @@ func (c Chart) checkRanges(xr, yr, yra Range) error {
 		if math.IsNaN(yraDelta) {
 			return errors.New("nan secondary y-range delta")
 		}
-		if yraDelta == 0 {
-			return errors.New("zero secondary y-range delta")
-		}
 	}
 
 	return nil

chart_test.go

@@ -443,22 +443,6 @@ func TestChartCheckRanges(t *testing.T) {
 	assert.Nil(c.checkRanges(xr, yr, yra))
 }
 
-func TestChartCheckRangesFailure(t *testing.T) {
-	assert := assert.New(t)
-
-	c := Chart{
-		Series: []Series{
-			ContinuousSeries{
-				XValues: []float64{1.0, 2.0},
-				YValues: []float64{3.14, 3.14},
-			},
-		},
-	}
-
-	xr, yr, yra := c.getRanges()
-	assert.NotNil(c.checkRanges(xr, yr, yra))
-}
-
 func TestChartCheckRangesWithRanges(t *testing.T) {
 	assert := assert.New(t)
 

util/math.go

@@ -93,12 +93,18 @@ func (m mathUtil) GetRoundToForDelta(delta float64) float64 {
 
 // RoundUp rounds up to a given roundTo value.
 func (m mathUtil) RoundUp(value, roundTo float64) float64 {
+	if roundTo < 0.000000000000001 {
+		return value
+	}
 	d1 := math.Ceil(value / roundTo)
 	return d1 * roundTo
 }
 
 // RoundDown rounds down to a given roundTo value.
 func (m mathUtil) RoundDown(value, roundTo float64) float64 {
+	if roundTo < 0.000000000000001 {
+		return value
+	}
 	d1 := math.Floor(value / roundTo)
 	return d1 * roundTo
 }

util/math_test.go

@@ -78,6 +78,7 @@ func TestRoundUp(t *testing.T) {
 	assert.Equal(0.5, Math.RoundUp(0.49, 0.1))
 	assert.Equal(1.0, Math.RoundUp(0.51, 1.0))
 	assert.Equal(0.4999, Math.RoundUp(0.49988, 0.0001))
+	assert.Equal(0.123, Math.RoundUp(0.123, 0))
 }
 
 func TestRoundDown(t *testing.T) {
@@ -85,6 +86,7 @@ func TestRoundDown(t *testing.T) {
 	assert.Equal(0.5, Math.RoundDown(0.51, 0.1))
 	assert.Equal(1.0, Math.RoundDown(1.01, 1.0))
 	assert.Equal(0.5001, Math.RoundDown(0.50011, 0.0001))
+	assert.Equal(0.123, Math.RoundDown(0.123, 0))
 }
 
 func TestPercentDifference(t *testing.T) {