function calculateCooper(){

	var blnOK = true;

	var objForm	= document.getElementById("frmcooper");
		
	var objGender	= objForm.gender;
	var objDistance	= objForm.distance;
	var objAge		= objForm.age;
	var objResult	= document.getElementById("result");
	
	var intDistance = parseInt(objDistance.value); 
	var strGender	= "";
	var intAge		= parseInt(objAge.value);
	var kat 		= 0;

	for(var i=0; i < objGender.length ; i++){
		if(objGender[i].checked)
			strGender = String(objGender[i].value);
	}
	
	if(is_empty_string(strGender)){
		alert("please state your gender !");
		blnOK = false;
	}
	
	if(blnOK){

		if(intAge < 30)
			kat = 0;
	
		if(intAge >= 30 && intAge < 40) 
			kat = 1;
	
		if(intAge >= 40 && intAge < 50) 
			kat = 2;
	
		if(intAge >= 50) 
			kat = 3;
		
		var mkat = new Array();
		var fkat = new Array();
		
		for(var i=0; i<4 ;i++){
			mkat[i] = new Array(4);
			fkat[i] = new Array(4);
		}
		
		mkat[0][0] = 1600;
		mkat[0][1] = 2000;
		mkat[0][2] = 2400;
		mkat[0][3] = 2800;
	 
		mkat[1][0] = 1500;
		mkat[1][1] = 1900;
		mkat[1][2] = 2300;
		mkat[1][3] = 2700;
	
		mkat[2][0] = 1400;
		mkat[2][1] = 1700;
		mkat[2][2] = 2100;
		mkat[2][3] = 2500;
	
		mkat[3][0] = 1300;
		mkat[3][1] = 1600;
		mkat[3][2] = 2000;
		mkat[3][3] = 2400;
	
		fkat[0][0] = 1500;
		fkat[0][1] = 1800;
		fkat[0][2] = 2200;
		fkat[0][3] = 2700;
	
		fkat[1][0] = 1400;
		fkat[1][1] = 1700;
		fkat[1][2] = 2000;
		fkat[1][3] = 2500;
	
		fkat[2][0] = 1200;
		fkat[2][1] = 1500;
		fkat[2][2] = 1900;
		fkat[2][3] = 2300;
	
		fkat[3][0] = 1100;
		fkat[3][1] = 1400;
		fkat[3][2] = 1700;
		fkat[3][3] = 2200;
	
		if(strGender == "male"){
			cooperScore = 0;
			for(var i=0; i<4 ;i++){
				if(intDistance > mkat[kat][i]) 
					cooperScore ++;
			}
		}else{
			cooperScore = 0;
			for(var i=0; i<4 ;i++){
				if(intDistance > fkat[kat][i]) 
					cooperScore ++;
			}	
		}
		switch(cooperScore){
			case 0: 
				var result = "very bad"; 
			break;
			case 1: 
				var result = "bad"; 
			break;
			case 2: 
				var result = "normal"; 
			break;
			case 3: 
				var result = "good"; 
			break;
			case 4: 
				var result = "very good"; 
			break;
		}
		
		objResult.innerHTML = result;
	}
}