lang: funcs: Add sqrt function

Signed-off-by: Lander Van den Bulcke <landervdb@inuits.eu>

lang/funcs/core/coremath/sqrt_func.go

@@ -0,0 +1,51 @@
+// Mgmt
+// Copyright (C) 2013-2018+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package coremath
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/purpleidea/mgmt/lang/funcs/simple"
+	"github.com/purpleidea/mgmt/lang/types"
+)
+
+func init() {
+	simple.ModuleRegister(moduleName, "sqrt", &types.FuncValue{
+		T: types.NewType("func(x float) float"),
+		V: Sqrt,
+	})
+}
+
+// Sqrt returns sqrt(x), the square root of x.
+func Sqrt(input []types.Value) (types.Value, error) {
+	x := input[0].Float()
+	y := math.Sqrt(x)
+	if math.IsNaN(y) {
+		return nil, fmt.Errorf("result is not a number")
+	}
+	if math.IsInf(y, 1) {
+		return nil, fmt.Errorf("result is positive infinity")
+	}
+	if math.IsInf(y, -1) {
+		return nil, fmt.Errorf("result is negative infinity")
+	}
+	return &types.FloatValue{
+		V: y,
+	}, nil
+}