function isEmail(email){
	var filtro=/^[A-Za-z][A-Za-z0-9_.-]*@[A-Za-z0-9_-]+\.[A-Za-z0-9_.]+[A-za-z]$/;
	if (filtro.test(email))
		return true;
	else
		return false;
}

function validar_cedula(cadena){
	var regularexp = /^(\d{6,7})[^\w]?-(\d)$/;
	
	if(!regularexp.test(cadena)) return false;
	
	var matches = cadena.match(regularexp);
	var ci = matches[1];
	var guion = matches[2];

	if(ci.length<7) ci='0'+ci;
	
	var t1 = Math.abs(((
		((parseInt(ci.charAt(0),10)*2)%10)+
		((parseInt(ci.charAt(1),10)*9)%10)+
		((parseInt(ci.charAt(2),10)*8)%10)+
		((parseInt(ci.charAt(3),10)*7)%10)+
		((parseInt(ci.charAt(4),10)*6)%10)+
		((parseInt(ci.charAt(5),10)*3)%10)+
		((parseInt(ci.charAt(6),10)*4)%10))%10)-10)%10;
	
	return(t1.toString()==guion);
}

//retorna el valor elegido o null en caso de no elegir ninguno
function validar_radios(name){
	var valor;
	var elementos = document.getElementsByName(name);
   for(var i=0;i<elementos.length;i++){
		if (elementos[i].checked) {
			valor = elementos[i].value;
      }  
	}
	
	return valor;
}

function marcar_error(id){
	var img_error = $('img.error');
	for(var i=0; i<img_error.length; i++){
		if(id == img_error[i].id){
			$('#'+img_error[i].id).show();
		}
		else{
			$('#'+img_error[i].id).hide();
		}
	}
}

String.prototype.trim = function() {
  return this.replace(/^\s+/, '').replace(/\s+$/, '');
};

function only_numbers(evt){	
// NOTE: Backspace = 8, Enter = 13, '0' = 48, '9' = 57, '.'=46, ','  = 44
	var key = IE ? evt.keyCode : evt.which;
	return (key <= 13 || (key >= 48 && key <= 57));
}