//copyright 2001 suessweb.com for airhog.com

function roundOff(val) 		//function to round off number to predetermined decimal places
	{
	val=val*1000.0;			//prepare for rounding
	val=Math.round(val);		//rounds to integer value
	val=val/1000.0;			//divide by 1000 for three decimal places
	return val;
	}


function muzzle() 			//main function to determine and convert muzzle velocity, weight, and energy
{

	vel = document.form0.v.value/1;		//English units - velocity
	wt = document.form0.w.value/1;		//English units - weight
	en = document.form0.e.value/1;		//English units - energy
	mvel = document.form0.mv.value/1;	//metric units - velocity
	mwt = document.form0.mw.value/1;	//metric units - weight
	men = document.form0.me.value/1;	//metric units - energy

if (document.form0.m[0].checked) 			//English units selected
{
	if (document.form0.v.value == "") 			//no value for v
	{ 
		if (document.form0.w.value == "") 	//no value for w
		{ 
		  alert("Please enter two numbers in English units \n\n      or choose Metric units.");
		}

		else if (document.form0.e.value == "") 	//no value for e
		{ 
		alert("Please enter two numbers in English units \n\n      or choose Metric units.");
		}
		else 							//w, e have values (filtered from above)
		{						
		tempa = en * 450240;
		tempb = tempa / wt;
		vel = Math.sqrt(tempb);
		men = en / 0.7376;
		mwt = wt / 15.432;
		mvel = vel * 0.303;
		document.form0.v.value = roundOff(vel);
		document.form0.me.value = roundOff(men);
		document.form0.mw.value = roundOff(mwt);
		document.form0.mv.value = roundOff(mvel);
		}
	}
	else if (document.form0.w.value == "") 	//no value for w
		{ 
		if (document.form0.e.value == "") 	//no value for e
			{	
 			alert("Please enter two numbers in English units\n\n       or choose Metric units.");
			} 
			
		else 						//v, e have values (filtered from above two decision statements)
			{						
			tempa = en * 450240;
			tempb = Math.pow(vel, 2);
			wt = tempa / tempb;	
			men = en / 0.7376;
			mwt = wt / 15.432;
			mvel = vel * 0.303;
			document.form0.w.value = roundOff(wt);
			document.form0.me.value = roundOff(men);
			document.form0.mw.value = roundOff(mwt);
			document.form0.mv.value = roundOff(mvel);
			}
		}
		
	else if (document.form0.e.value == "") 	//no value for e
		{
		tempa = Math.pow(vel, 2);
		tempb = tempa * wt;
		en = tempb / 450240;
          	men = en / 0.7376;
          	mwt = wt / 15.432;
          	mvel = vel * 0.303;
          	document.form0.e.value = roundOff(en);
          	document.form0.me.value = roundOff(men);
          	document.form0.mw.value = roundOff(mwt);
          	document.form0.mv.value = roundOff(mvel);
     		}

	 else 						// 3 numbers were entered 
		{	
		alert("Please enter only two numbers.\n\nPress reset and enter two numbers.");
		}

}	// end of English units calculations

 if (document.form0.m[1].checked) 		//Metric units selected
{
	if (document.form0.mv.value == "") 		// no value for v - metric
	{
		if (document.form0.mw.value == "") 	// no value for w - metric
		{
		alert("Please enter two numbers in Metric units \n\n       or choose English units.");
		} 
		
		else	if (document.form0.me.value == "") // no value for e - metric
		{
		alert("Please enter two numbers in Metric units \n\n       or choose English units.");
		} 
		
		else 
		{
		tempa = men * 2000;
		tempb = tempa / mwt;
		mvel = Math.sqrt(tempb);
		vel = mvel * 3.3;
                en = men / 1.3556;
                wt = mwt * 15.432;
                document.form0.v.value = roundOff(vel);
                document.form0.e.value = roundOff(en);
                document.form0.w.value = roundOff(wt);
                document.form0.mv.value = roundOff(mvel);
		}

	} 
	
	else								// v has value - metric (filtered from above)
		if (document.form0.mw.value == "") 	// no value for w - metric
		{	
			if (document.form0.me.value == "") // no value for e - metric
			{	
			alert("Please enter two numbers in Metric units \n\n       or choose English units.");
			} 
			
			else 					// v, e have values - metric
			{
			tempa = men * 2000;
			tempb = Math.pow(mvel, 2);
			mwt = tempa / tempb;
			wt = mwt * 15.432;
			en = men / 1.3556;
			vel = mvel * 3.3;
			document.form0.w.value = roundOff(wt);
			document.form0.v.value = roundOff(vel);
			document.form0.e.value = roundOff(en);
			document.form0.mw.value = roundOff(mwt);
			}
		} 
		
		else if (document.form0.me.value == "") // v, w have values - metric (filtered from above two decision statements)
		{
          	tempa = Math.pow(mvel, 2);
   	        men = (mwt * tempa)/2000;
  	        en = men / 1.3556;
 	        wt = mwt * 15.432;
		vel = mvel * 3.33;
   	 	document.form0.e.value = roundOff(en);
   		document.form0.v.value = roundOff(vel);
    		document.form0.w.value = roundOff(wt);
		document.form0.me.value = roundOff(men);
		}		 
		
		else		// 3 metric numbers are entered
		{
		alert("Please enter only two numbers.\n\nPress reset and enter two numbers.");
		}

	}	//end metric units

 }