function roundNumber(rnum, rlength) { 

	var newnumber = Math.round(rnum*Math.pow(10,rlength))/Math.pow(10,rlength);

	return newnumber;

}		

function calcArrowSpeed() {

	var value1 = document.getElementById( "field1" ).value; // bow ibo speed

	var value2 = document.getElementById( "field2" ).value; // arrow weight

	var value3 = document.getElementById( "field3" ).value; // draw length

	var value4 = document.getElementById( "field4" ).value; // draw weight

	var value5 = document.getElementById( "field5" ).value; // weight added to string

	var calc = 0;

	

	if( value1 != '' ) {

		calc = value1;

		if( value2 != '' ) {

			document.getElementById( "field6" ).value = value2;

			calc = calc - ( value2 - 350 ) / 3;

			if( value3 != '' ) {

				var tmp = 30 - value3;

				if( tmp > 0 ) {

					calc = calc - ( tmp * 10 );

				}

				if( value4 != '' ) {

					if( value4 <= 65 ) {

						var tmp = roundNumber( ( 70 - value4 ) / 5, 0 ) * 10;

						calc = calc - tmp;

					}

					if( value5 != '' ) {

						calc = calc - ( value5 / 3 );

						calc = roundNumber( calc, 2 );

						document.getElementById( "calc1" ).value = calc;

					}

				}

			}

		}

	}

}

function calcKineticEnergy() {

	var value6 = document.getElementById( "field6" ).value; // arrow weight

	var value7 = document.getElementById( "field7" ).value; // arrow speed

	var calc2 = 0;

	

	if( value6 != '' && value7 != '' ) {

		calc2 = ( value6 * value7 * value7 ) / 450240;

		calc2 = roundNumber( calc2, 2 );

		document.getElementById( "calc2" ).value = calc2;

	}

}

function calcFOC() {

	var value8 = document.getElementById( "field8" ).value; // arrow length

	var value9 = document.getElementById( "field9" ).value; // balance point length

	var calc3 = 0;

	

	if( value8 != '' && value9 != '' ) {

		calc3 = ( value9 - value8 / 2 ) / value8 * 100;

		calc3 = roundNumber( calc3, 2 );

		document.getElementById( "calc3" ).value = calc3;

	}

}

function calcArrowWeight() {

	var value10 = document.getElementById( "field10" ).value; // shaft weight

	var value11 = document.getElementById( "field11" ).value; // arrow shaft length

	var value12 = document.getElementById( "field12" ).value; // point weight

	var value13 = document.getElementById( "field13" ).value; // insert weight

	var value14 = document.getElementById( "field14" ).value; // nock weight

	var value15 = document.getElementById( "field15" ).value; //  number of veins

	var value16 = document.getElementById( "field16" ).value; //  vane weight per vane

	var value17 = document.getElementById( "field17" ).value; // wrap weight

	var calc4 = 0;

				

	if( value10 != '' && value11 != '' ) {

		value10 = parseFloat( value10 );

		value11 = parseFloat( value11 );

		calc4 = value10 * value11;			

		if( value12 != '' ) {

			value12 = parseFloat( value12 );

			calc4 = calc4 + value12;

			if( value13 != '' ) {

				value13 = parseFloat( value13 );

				calc4 = calc4 + value13;

				if( value14 != '' ) {

					value14 = parseFloat( value14 );

					calc4 = calc4 + value14;

					if( value15 != '' && value16 != '' ) {

						value15 = parseFloat( value15 );

						value16 = parseFloat( value16 );

						calc4 = calc4 + ( value15 * value16 );

						if( value17 != '' ) {

							value17 = parseFloat( value17 );

							calc4 = calc4 + value17;

						}

					}

				}

			}

		}

	}

	calc4 = roundNumber( calc4, 2 );

	document.getElementById( "calc4" ).value = calc4;

}