regex - Convert functions of math to functions of javascript in java -

i have made string mathematical expression parser follows:

public class expsolver {   public string solve(string s){       try {           scriptenginemanager mgr = new scriptenginemanager();           scriptengine engine = mgr.getenginebyname("javascript");           return engine.eval(s).tostring();       } catch (scriptexception ex) {           logger.getlogger(expsolver.class.getname()).log(level.severe, null, ex);       }       return "0";   }   public static void main(string args[]){       system.out.println(new expsolver().solve(new java.util.scanner(system.in).nextline()));   } } 

now want add codes parse mathematical functions such sin, cos, tan, ^ (power), log etc. program. best , code efficient solution that? have seen regex expressions unable on such large scale.

how using expression parser of math.js , use via java scriptengine?

here example:

package org.mathjs;  import java.io.ioexception; import java.io.inputstreamreader; import java.net.malformedurlexception; import java.net.url;  import javax.script.scriptengine; import javax.script.scriptenginemanager; import javax.script.scriptexception;  public class mathjsdemo {     protected static string mathjs_url =              "http://cdnjs.cloudflare.com/ajax/libs/mathjs/1.0.1/math.js";      protected scriptengine engine;      public mathjsdemo() throws malformedurlexception, scriptexception, ioexception {         scriptenginemanager manager = new scriptenginemanager ();         engine = manager.getenginebyname ("js");          engine.eval(new inputstreamreader(new url(mathjs_url).openstream()));         engine.eval("var parser = math.parser();");         engine.eval("var precision = 14;");     }      public string eval (string expr) throws scriptexception {         string script = "math.format(parser.eval('" + expr + "'), precision);";         return (string) engine.eval(script);     }      public static void main(string[] args) throws scriptexception, malformedurlexception, ioexception {         mathjsurl math = new mathjsdemo();         system.out.println(math.eval("a = 4.5"));         system.out.println(math.eval("1.2 * (2 + a)"));         system.out.println(math.eval("5.08 cm in inch"));         system.out.println(math.eval("sin(45 deg) ^ 2"));            system.out.println(math.eval("9 / 3 + 2i"));             system.out.println(math.eval("det([-1, 2; 3, 1])"));     } }