// The following function is used for generating error messages based on input field values. If there are no errors, the results are calculated.
function calc(x) {
var err, X, N
err=0;
N = 1;

if(x==1){
	document.getElementById("mes1").innerHTML=""
	document.getElementById("mes2").innerHTML=""
	document.getElementById("mes3").innerHTML=""
	
	if(isNaN(eval(document.forms[0].elements['L'].value)) || document.forms[0].elements['L'].value=='' || document.forms[0].elements['L'].value==null){
		document.getElementById("mes1").innerHTML= "Please input a number"
		err = eval(err) + 1
	}
	
	if(isNaN(eval(document.forms[0].elements['W'].value)) || document.forms[0].elements['W'].value=='' || document.forms[0].elements['W'].value==null){
		document.getElementById("mes2").innerHTML= "Please input a number"
		err = eval(err) + 1
	}
	
	if(isNaN(eval(document.forms[0].elements['G'].value)) || document.forms[0].elements['G'].value=='' || document.forms[0].elements['G'].value==null){
		document.getElementById("mes3").innerHTML= "Please input a number"
		err = eval(err) + 1
	}
	
	if(eval(document.forms[0].elements['L'].value)==0){
		document.getElementById("mes1").innerHTML= "Greater than 0 required"
		err = eval(err) + 1
	}
	
	if(eval(document.forms[0].elements['W'].value)==0){
		document.getElementById("mes2").innerHTML= "Greater than 0 required"
		err = eval(err) + 1
	}
	
	if(eval(document.forms[0].elements['G'].value)==0){
		document.getElementById("mes3").innerHTML= "Greater than 0 required"
		err = eval(err) + 1
	}
	
	if(eval(err)<1){
		X = document.forms[0].elements['L'].value * 12 * document.forms[0].elements['W'].value * document.forms[0].elements['G'].value / 3000000
		document.forms[0].elements['RW'].value = CORE(X, N)
	}
}

if(x==2){
	document.getElementById("mes11").innerHTML=""
	document.getElementById("mes12").innerHTML=""
	document.getElementById("mes13").innerHTML=""
	
	if(isNaN(eval(document.forms[1].elements['We'].value)) || document.forms[1].elements['We'].value=='' || document.forms[1].elements['We'].value==null){
		document.getElementById("mes11").innerHTML= "Please input a number"
		err = eval(err) + 1
	}
	
	if(isNaN(eval(document.forms[1].elements['W'].value)) || document.forms[1].elements['W'].value=='' || document.forms[1].elements['W'].value==null){
		document.getElementById("mes12").innerHTML= "Please input a number"
		err = eval(err) + 1
	}
	
	if(isNaN(eval(document.forms[1].elements['G'].value)) || document.forms[1].elements['G'].value=='' || document.forms[1].elements['G'].value==null){
		document.getElementById("mes13").innerHTML= "Please input a number"
		err = eval(err) + 1
	}
	
	if(eval(document.forms[1].elements['We'].value)==0){
		document.getElementById("mes11").innerHTML= "Greater than 0 required"
		err = eval(err) + 1
	}
	
	if(eval(document.forms[1].elements['W'].value)==0){
		document.getElementById("mes12").innerHTML= "Greater than 0 required"
		err = eval(err) + 1
	}
	
	if(eval(document.forms[1].elements['G'].value)==0){
		document.getElementById("mes13").innerHTML= "Greater than 0 required"
		err = eval(err) + 1
	}
	
	if(eval(err)<1){
		X = 3000000 * document.forms[1].elements['We'].value / (12 * document.forms[1].elements['W'].value * document.forms[1].elements['G'].value)
		document.forms[1].elements['RL'].value = CORE(X, N)
	}

}

if(x==3){
	document.getElementById("mes31").innerHTML=""
	
	if(isNaN(eval(document.forms[2].elements['M'].value)) || document.forms[2].elements['M'].value=='' || document.forms[2].elements['M'].value==null){
		document.getElementById("mes31").innerHTML= "Please input a number"
		err = eval(err) + 1
	}
	
	if(eval(document.forms[2].elements['M'].value)==0){
		document.getElementById("mes31").innerHTML= "Greater than 0 required"
		err = eval(err) + 1
	}
	
	if(eval(err)<1){
		X = document.forms[2].elements['M'].value / 0.254
		//document.forms[2].elements['G'].value = CORE(X, N)
		document.forms[2].elements['G'].value = Math.round(X)
	}

}

if(x==4){
	document.getElementById("mes41").innerHTML=""
	
	if(isNaN(eval(document.forms[3].elements['G'].value)) || document.forms[3].elements['G'].value=='' || document.forms[3].elements['G'].value==null){
		document.getElementById("mes41").innerHTML= "Please input a number"
		err = eval(err) + 1
	}
	
	if(eval(document.forms[3].elements['G'].value)==0){
		document.getElementById("mes41").innerHTML= "Greater than 0 required"
		err = eval(err) + 1
	}
	
	if(eval(err)<1){
		X = document.forms[3].elements['G'].value * 0.254
		document.forms[3].elements['M'].value = CORE(X, N)
	}

}

}

// The following function is used for clearing off previous error messages and resetting form input values to zero
function res(x){
if(x==1){
	document.getElementById("mes1").innerHTML=""
	document.getElementById("mes2").innerHTML=""
	document.getElementById("mes3").innerHTML=""
	document.forms[0].elements[0].value=0
	document.forms[0].elements[1].value=0
	document.forms[0].elements[2].value=0
	document.forms[0].elements['RW'].value=0
}

if(x==2){
	document.getElementById("mes11").innerHTML=""
	document.getElementById("mes12").innerHTML=""
	document.getElementById("mes13").innerHTML=""
	document.forms[1].elements[0].value=0
	document.forms[1].elements[1].value=0
	document.forms[1].elements[2].value=0
	document.forms[1].elements['RL'].value=0
}

if(x==3){
	document.getElementById("mes31").innerHTML=""
	document.forms[2].elements[0].value=0
	document.forms[2].elements['G'].value=0
}

if(x==4){
	document.getElementById("mes41").innerHTML=""
	document.forms[3].elements[0].value=0
	document.forms[3].elements['M'].value=0
}

}