Add new var math functions

shared/naturalcrit/markdown.js

@@ -46,6 +46,27 @@ const mathParser = new MathParser({
 		array       : false, fndef       : false
 	}
 });
+// Add absolute function
+mathParser.functions.abs = function (a) {
+	return Math.abs(a);
+};
+// Add sign function
+mathParser.functions.sign = function (a) {
+	if(a == 0) return '';
+	if(a > 0) {
+		return '\\+';
+	} else {
+		return '\\-';
+	}
+};
+// Add signed function
+mathParser.functions.signed = function (a) {
+	if(a >= 0) {
+		return `\\+${a}`;
+	} else {
+		return `\\${a}`;
+	}
+};
 
 //Processes the markdown within an HTML block if it's just a class-wrapper
 renderer.html = function (html) {