SimpleContext context = new SimpleContext();
// variables e, pi
context.setVariable("e", factory.createValueExpression(Math.E, double.class));
context.setVariable("pi", factory.createValueExpression(Math.PI, double.class));
// functions sin, cos, tan, exp, log, abs, sqrt, min, max, pow
context.setFunction("", "sin", Math.class.getMethod("sin", double.class));
context.setFunction("", "cos", Math.class.getMethod("cos", double.class));
context.setFunction("", "tan", Math.class.getMethod("tan", double.class));