feat(math): decimal round, floor and ceil

math/_decimal-adjust.js

@@ -0,0 +1,29 @@
+// Credit:
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/round
+// #Decimal_rounding
+
+"use strict";
+
+var isValue       = require("../object/is-value")
+  , ensureInteger = require("../object/ensure-integer");
+
+var split = String.prototype.split;
+
+module.exports = function (type) {
+	return function (value/*, exp*/) {
+		value = Number(value);
+		var exp = arguments[1];
+		if (isValue(exp)) exp = ensureInteger(exp);
+		if (!value) return value;
+		if (!exp) return Math[type](value);
+		if (!isFinite(value)) return value;
+
+		// Shift
+		var tokens = split.call(value, "e");
+		value = Math[type](tokens[0] + "e" + ((tokens[1] || 0) - exp));
+
+		// Shift back
+		tokens = value.toString().split("e");
+		return Number(tokens[0] + "e" + (Number(tokens[1] || 0) + exp));
+	};
+};

math/ceil-10.js

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_decimal-adjust")("ceil");

math/floor-10.js

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_decimal-adjust")("floor");

math/index.js

@@ -5,15 +5,18 @@ module.exports = {
 	asinh: require("./asinh"),
 	atanh: require("./atanh"),
 	cbrt: require("./cbrt"),
+	ceil10: require("./ceil-10"),
 	clz32: require("./clz32"),
 	cosh: require("./cosh"),
 	expm1: require("./expm1"),
+	floor10: require("./floor-10"),
 	fround: require("./fround"),
 	hypot: require("./hypot"),
 	imul: require("./imul"),
 	log10: require("./log10"),
 	log2: require("./log2"),
 	log1p: require("./log1p"),
+	round10: require("./round-10"),
 	sign: require("./sign"),
 	sinh: require("./sinh"),
 	tanh: require("./tanh"),

math/round-10.js

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_decimal-adjust")("round");

test/math/_decimal-adjust.js

@@ -0,0 +1,6 @@
+"use strict";
+
+module.exports = function (t, a) {
+	// Just sanity check, as real tests are in 'round', 'ceil' and 'floor' variants
+	a(t("round")(55.55, -1), 55.6);
+};

test/math/ceil-10.js

@@ -0,0 +1,8 @@
+"use strict";
+
+module.exports = function (t, a) {
+	a(t(55.51, -1), 55.6);
+	a(t(51, 1), 60);
+	a(t(-55.59, -1), -55.5);
+	a(t(-59, 1), -50);
+};

test/math/floor-10.js

@@ -0,0 +1,8 @@
+"use strict";
+
+module.exports = function (t, a) {
+	a(t(55.59, -1), 55.5);
+	a(t(59, 1), 50);
+	a(t(-55.51, -1), -55.6);
+	a(t(-51, 1), -60);
+};

test/math/round-10.js

@@ -0,0 +1,14 @@
+"use strict";
+
+module.exports = function (t, a) {
+	a(t(55.55, -1), 55.6);
+	a(t(55.549, -1), 55.5);
+	a(t(55, 1), 60);
+	a(t(54.9, 1), 50);
+	a(t(-55.55, -1), -55.5);
+	a(t(-55.551, -1), -55.6);
+	a(t(-55, 1), -50);
+	a(t(-55.1, 1), -60);
+	a(t(1.005, -2), 1.01);
+	a(t(-1.005, -2), -1.0);
+};