Add math.sqrt SQL function

sql/funcs.go

@@ -143,6 +143,7 @@ var funcs = map[string]map[int]interface{}{
 	"math.round":         {1: nil},
 	"math.sample":        {2: nil},
 	"math.spread":        {1: nil},
+	"math.sqrt":          {1: nil},
 	"math.stddev":        {1: nil},
 	"math.sum":           {1: nil},
 	"math.top":           {2: nil},

util/fncs/fnc.go

@@ -154,6 +154,8 @@ func Run(ctx context.Context, name string, args ...interface{}) (interface{}, er
 		return mathSample(ctx, args...)
 	case "math.spread":
 		return mathSpread(ctx, args...)
+	case "math.sqrt":
+		return mathSqrt(ctx, args...)
 	case "math.stddev":
 		return mathStddev(ctx, args...)
 	case "math.sum":

util/fncs/math.go

@@ -143,6 +143,13 @@ func mathSpread(ctx context.Context, args ...interface{}) (out interface{}, err
 	return outputFloat(math.Spread(vals))
 }
 
+func mathSqrt(ctx context.Context, args ...interface{}) (out interface{}, err error) {
+	if val, ok := ensureFloat(args[0]); ok {
+		return outputFloat(math.Sqrt(val))
+	}
+	return
+}
+
 func mathStddev(ctx context.Context, args ...interface{}) (out interface{}, err error) {
 	vals := ensureFloats(args[0])
 	return outputFloat(math.PopulationStandardDeviation(vals))

util/fncs/math_test.go

@@ -219,6 +219,15 @@ func TestMath(t *testing.T) {
 		So(res, ShouldEqual, 4.5)
 	})
 
+	Convey("math.sqrt() works properly", t, func() {
+		res, _ = Run(context.Background(), "math.sqrt", "test")
+		So(res, ShouldEqual, nil)
+		res, _ = Run(context.Background(), "math.sqrt", test)
+		So(res, ShouldEqual, nil)
+		res, _ = Run(context.Background(), "math.sqrt", 10)
+		So(res, ShouldEqual, 3.1622776601683795)
+	})
+
 	Convey("math.stddev() works properly", t, func() {
 		res, _ = Run(context.Background(), "math.stddev", "test")
 		So(res, ShouldEqual, nil)

util/math/sqrt.go

@@ -0,0 +1,21 @@
+// Copyright © 2016 Abcum Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package math
+
+import "math"
+
+func Sqrt(val float64) float64 {
+	return math.Sqrt(val)
+}