Lerp.

ext/stats/percentile.go

@@ -6,10 +6,9 @@ import (
 	"math"
 	"slices"
 
-	"github.com/ncruces/sort/quick"
-
 	"github.com/ncruces/go-sqlite3"
 	"github.com/ncruces/go-sqlite3/internal/util"
+	"github.com/ncruces/sort/quick"
 )
 
 const (
@@ -92,7 +91,7 @@ func (q *percentile) at(pos float64) (float64, error) {
 	}
 
 	m1 := slices.Min(q.nums[int(i)+1:])
-	return math.FMA(f, m1, math.FMA(-f, m0, m0)), nil
+	return util.Lerp(m0, m1, f), nil
 }
 
 func (q *percentile) atMore(pos []float64) error {

internal/util/math.go

@@ -1,5 +1,7 @@
 package util
 
+import "math"
+
 func abs(n int) int {
 	if n < 0 {
 		return -n
@@ -20,3 +22,8 @@ func LCM(m, n int) int {
 	}
 	return abs(n) * (abs(m) / GCD(m, n))
 }
+
+// https://developer.nvidia.com/blog/lerp-faster-cuda/
+func Lerp(v0, v1, t float64) float64 {
+	return math.FMA(t, v1, math.FMA(-t, v0, v0))
+}

internal/util/pointer_test.go

@@ -1,15 +1,13 @@
-package util_test
+package util
 
 import (
 	"math"
 	"testing"
-
-	"github.com/ncruces/go-sqlite3/internal/util"
 )
 
 func TestUnwrapPointer(t *testing.T) {
-	p := util.Pointer[float64]{Value: math.Pi}
-	if got := util.UnwrapPointer(p); got != math.Pi {
+	p := Pointer[float64]{Value: math.Pi}
+	if got := UnwrapPointer(p); got != math.Pi {
 		t.Errorf("want π, got %v", got)
 	}
 }

tests/json_test.go

@@ -7,13 +7,12 @@ import (
 	"testing"
 	"time"
 
-	"github.com/ncruces/julianday"
-
 	"github.com/ncruces/go-sqlite3"
 	"github.com/ncruces/go-sqlite3/driver"
 	_ "github.com/ncruces/go-sqlite3/embed"
 	_ "github.com/ncruces/go-sqlite3/internal/testcfg"
 	"github.com/ncruces/go-sqlite3/vfs/memdb"
+	"github.com/ncruces/julianday"
 )
 
 func TestJSON(t *testing.T) {

time.go

@@ -6,9 +6,8 @@ import (
 	"strings"
 	"time"
 
-	"github.com/ncruces/julianday"
-
 	"github.com/ncruces/go-sqlite3/internal/util"
+	"github.com/ncruces/julianday"
 )
 
 // TimeFormat specifies how to encode/decode time values.