function CalcIt(form) {

	var weight =  Number(form.wt.value);

	if (!checkWeight(weight)) return false;
	if (form.wu.selectedIndex == 0) { // 0 = weight in lbs
		kg = weight * 0.45359237;
	} else {  // 1 = weight in kg.
		kg = weight;
	}
	if (kg < 10) {
		alert("Weights should be heavier than 10 kilograms (22 pounds).");
		return false;
	}
	if (kg > 200) {
		alert("Weights should be lighter than 200 kilograms (441 pounds).");
		return false;
	}


	var height =  Number(form.ht.value);

	if ((isNaN(height)) || (height == null)  || (height == "") || (height < 0)) {
		feetAndInches(form);
		height =  Number(form.ht.value);
	}

	if (form.hu.selectedIndex == 0) {		//  if height units are "inches"
		heightInches = height;
		heightMeters = height * 2.54 / 100;
	} else {					// else if height units are "cm".
		heightInches = height / 2.54;
		heightMeters = height / 100;
	}
	if (heightMeters < 0.33) {
		alert("Heights should be taller than 33 centimeters (31.5 inches).");
		return false;
	}
	if (heightMeters > 2.41) {
		alert("Heights should be shorter than 241 centimeters ( 7 feet, 11 inches).");
		return false;
	}
	setFeetAndInches(form,heightInches);

	var cm = heightMeters * 100;
	// Calculate BMI
	var bmi = kg / Math.pow(heightMeters,2);
 	var answer = document.form.bmi.value = rounding(bmi,1);
	//document.form.bmis.value = rounding(bmi,1);
	var a = document.form.bmis1.value = rounding(bmi,1);
	 var b =  document.form.bmis2.value = rounding(bmi,1);
	  var c =  document.form.bmis3.value = rounding(bmi,1);
	  var d =   document.form.bmis4.value = rounding(bmi,1);
	if (answer < 18.5)
	{
		Layer1.style.display="none";
		Layer2.style.display="block";
	}
	else if ( (answer < 24.9) && (answer > 18.5))
	{
		Layer1.style.display="none";
		Layer3.style.display="block";
	}
	else if ( (answer < 29.9) && (answer > 24.9))
	{
		Layer1.style.display="none";
		Layer4.style.display="block";
	}
	else 	{
		Layer1.style.display="none";
		Layer5.style.display="block";
	}
 	// Prepare vars for percentile calculations.
	var p05 = 0;
	var p10 = 0;
	var p25 = 0;
	var p50 = 0;
	var p75 = 0;
	var p90 = 0;
	var p95 = 0;

	var m = 0;
	var b = 0;
	var theP = 0;
	var specific50 = 0; // Use for age-specific like 50th percentile value.
	var diff50 = 0;	 // holds the difference of p50 - specific50.
	
	a2 = cm*cm;
	a3 = a2*cm;
	
	// Calculate Weight for Height percentiles based on age.
	if (form.Gender.selectedIndex == 0) { // 0 = boys.
		if (cm<125) {  // 2nd order polynomials
			p05 = 0.0021*a2 - 0.155*cm + 8.2203;
			p10 = 0.0023*a2 - 0.1823*cm + 9.618;
			p25 = 0.0028*a2 - 0.2744*cm + 14.483;
			p50 = 0.0026*a2 - 0.21*cm + 10.8;
			p75 = 0.0037*a2 - 0.3934*cm + 19;
			p90 = 0.0058*a2 - 0.7611*cm + 35.6;
			p95 = 0.0082*a2 - 1.2204*cm + 58.051;
		} else {
			if (cm < 165) {   // sigmoid curves
				p05 = 20+(70-20)/(1+(Math.pow(10,(158-cm)*0.04)));
				p10 = 23+(67-23)/(1+(Math.pow(10,(156-cm)*0.05)));
				p25 = 24+(75-24)/(1+(Math.pow(10,(156-cm)*0.05)));
				p50 = 22.9+(89-22.9)/(1+(Math.pow(10,(156-cm)*0.045)));
				p75 = 27.5+(90-27.5)/(1+(Math.pow(10,(153-cm)*0.055)));
				p90 = 30+(94-30)/(1+(Math.pow(10,(150-cm)*0.055)));
				p95 = 34.5+(104-34.5)/(1+(Math.pow(10,(151-cm)*0.056)));
			} else {   // linear
				p05 = 0.73*cm - 67.96;
				p10 = 0.7928*cm - 75.507;
				p25 = 0.8941*cm - 86.397;
				p50 = 0.9165*cm - 81.496;
				p75 = 1.1124*cm - 105.3;
				p90 = 1.2251*cm - 114.72;
				p95 = 1.2363*cm - 108.84;
			}
		}
		specific50 = p50;
		
		if (cm < 112)  {  // 125 works better for girls.
			specific50 = p50;
		}
	} else {	// 1 = girls.
		// Get p05 thru p95 ready, we'll need them later.
		if (cm<125) {   // 2nd order polynomials
			p05 = 0.0020*a2 - 0.141*cm + 8.0736;
			p10 = 0.0022*a2 - 0.177*cm + 10;
			p25 = 0.0016*a2 - 0.0398*cm + 2.9072;
			p50 = 0.0018*a2 - 0.0554*cm + 3.3595;
			p75 = 0.0033*a2 - 0.3099*cm + 14.6;
			p90 = 0.0045*a2 - 0.46*cm + 19.2;
			p95 = 0.0061*a2 - 0.7332*cm + 31.202;
		} else {
			if (cm < 161) {  // sigmoid curves
				p05 = 21+(53-21)/(1+(Math.pow(10,(148-cm)*0.06)));
				p10 = 21.7+(53-21.7)/(1+(Math.pow(10,(146-cm)*0.07)));
				p25 = 22+(60-22)/(1+(Math.pow(10,(145-cm)*0.068)));
				p50 = 22+(70-22)/(1+(Math.pow(10,(143-cm)*0.065)));
				p75 = 25+(82-25)/(1+(Math.pow(10,(143-cm)*0.068)));
				p90 = 26+(99-26)/(1+(Math.pow(10,(142-cm)*0.06)));
				p95 = 28+(107-28)/(1+(Math.pow(10,(142-cm)*0.06)));
			} else {   // linear
				p05 = 0.6153*cm - 50.992;
				p10 = 0.6759*cm - 58.085;
				p25 = 0.6375*cm - 45.456;
				p50 = 0.6261*cm - 33.83;
				p75 = 0.6896*cm - 30.833;
				p90 = 0.8127*cm - 36.131;
				p95 = cm - 58;
				
			}
		}
		specific50 = p50;
		
		if (cm < 126)  {  // 111 works better for boys.
			specific50 = p50;
		}
	}

	diff50 = p50 - specific50;
	p05 = p05 - diff50;
	p10 = p10 - diff50;
	p25 = p25 - diff50;
	p50 = p50 - diff50;
	p75 = p75 - diff50;
	p90 = p90 - diff50;
	p95 = p95 - diff50;

	if (kg < p10) {
		m = (10-5) / (p10-p05);
		b = 5 - (m * p05);
	} else {
		if (kg < p25) {
			m = (25-10) / (p25-p10);
			b = 10 - (m * p10);
		} else {
			if (kg < p50) {
				m = (50-25) / (p50-p25);
				b = 25 - (m * p25);
			} else {
				if (kg < p75) {
					m = (75-50) / (p75-p50);
					b = 50 - (m * p50);
				} else {
					if (kg < p90) {
						m = (90-75) / (p90-p75);
						b = 75 - (m * p75);
					} else {	// 90th percentile or higher.
						m = (95-90) / (p95-p90);
						b = 90 - (m * p90);
					}
				}
			}
		}	
	}
	theP = m * kg + b;	// Don't forget to truncate >98% or < 2% values.




return null;
}

// This is only called if the form.Years.value was empty.
// The user may have used the pop-up menu however, to set an age.


function SetAge(form) {
	if (form.Years.value > 0) {	// Only change the Age field, if a value is already there.
	
		if (form.AgeCat.selectedIndex == 0) { // 70+ years,
			form.Years.value = 75;
		} else {
			if (form.AgeCat.selectedIndex < 6) { // 1 thru 5 are decades 20s thru 60s.
				form.Years.value = 65 - (form.AgeCat.selectedIndex -1)*10;
			} else {
				if (form.AgeCat.selectedIndex == 6 ) {
					form.Years.value = 19;
				} else {
					if (form.AgeCat.selectedIndex < 23) { // 7 thru 22 are ages 17 thru 2.
						form.Years.value = 17 - (form.AgeCat.selectedIndex-7);
					} else {
						if (form.AgeCat.selectedIndex == 23) { // age 1.5 yrs.
							form.Years.value = 1.5;
						} else {
							if (form.AgeCat.selectedIndex == 24) {	// age 1 yrs.
								form.Years.value = 1;
							} else {
								if (form.AgeCat.selectedIndex == 25) {
									form.Years.value = 30;
								} else {
									if (form.Years.value > 19) form.Years.value = "";
								}
							}
						}
					}
				}
			}
		}
	}
	return true;
}

function SetAgeCat(form,tAge) {	
	if (tAge > 69.99) { form.AgeCat.selectedIndex = 0; } // 70+ years,
	else { if (tAge <=1) form.AgeCat.selectedIndex = 24; 	// age 1 yrs.
	else { if (tAge < 2) form.AgeCat.selectedIndex = 23; // age 1.5 yrs.
	else { if (tAge < 18) form.AgeCat.selectedIndex = -Math.floor(tAge) + 24;  // 7 thru 22 are ages 17 thru 2.
	else { if (tAge < 20) form.AgeCat.selectedIndex = 6;   // age 18-19
	else { // 1 thru 5 are decades 60s thru 20s. 1=60s 2=50s 3=40s
		form.AgeCat.selectedIndex = Math.ceil(-1*(tAge-78.999))/10; 
 	}}}}}
	return true;
}

function setFeetAndInches(form,inchies) {
	var feet = Math.min( Math.max( Math.floor( inchies / 12 ), 1), 7);
	form.htf.selectedIndex = feet - 1;

	inchies = rounding( inchies - feet*12,0);
	form.hti.selectedIndex = Math.min( Math.max( inchies,0), 11 );
	return true;
}

function feetAndInches(form) {
	var inchies = 0;
	inchies = ((form.htf.selectedIndex+1) * 12) + form.hti.selectedIndex;

	if (form.hu.selectedIndex == 0) form.ht.value = inchies;
	if (form.hu.selectedIndex == 1) form.ht.value = rounding( inchies * 2.54,0);
	return true;
}


function SetPercentile( pc ) {

	if (pc > 98) { pc = "> 98th percentile"; }
	else { if (pc < 2) { pc = "< 2nd percentile"; }
	else { if (pc == 11) { pc = "11th percentile"; }
	else { if (pc == 12) { pc = "12th percentile"; }
	else { if (pc == 13) { pc = "13th percentile"; }
	else { if (rightDigit(pc) == 1) { pc = pc + "st percentile"; }
	else { if (rightDigit(pc) == 2) { pc = pc + "nd percentile"; }
	else { if (rightDigit(pc) == 3) { pc = pc + "rd percentile"; } 
	else { pc = pc + "th percentile"; }
	}}}}}}}

	return pc;
}

function poundsAndKilos(form) {
	var weight = Number(form.wt.value);
	if ( weight > 0) {
		if (form.wu.selectedIndex == 0) {	// 0 = pounds.
			form.wt.value = rounding( weight / 0.45359237,0);
		} else {								// 1 = kilograms.
			if (weight > 219) {
				form.wt.value = rounding( weight * 0.45359237,0);
			} else {
				form.wt.value = rounding( weight * 0.45359237,1);
			}
		}
		form.wt.select();
		//form.wt.focus();
	}
	return true;
}

function inchesCm(form) {
	var height = Number(form.ht.value);
	if (height > 0) {
		if (form.hu.selectedIndex == 0) { // is now inches, was cm.
			setFeetAndInches(form, height / 2.54); 
			form.ht.value = rounding( height / 2.54,1) ; 
		} else {								// is now cm, was inches.
			setFeetAndInches(form, height);  // Always pass inches in height to this function.
			form.ht.value = rounding( height * 2.54,0);  }  
		form.ht.select();
		form.ht.focus();
	}
	return true;
}

function rightDigit(num) {
	num = num - (Math.floor(num/10)*10);
	return num;
}

function rounding(number,decimal) {
	multi = Math.pow(10,decimal);
	number = Math.round(number * multi) / multi;
	return number;
}


function checkWeight(val) {
	if ((isNaN(val)) || (val == null)  || (val == "") || (val < 0)) {
		alert( "Please enter a value for Weight.");
		return false;
	}
	return true;
}

function OpenLink(theURL) {
	window.open(theURL);
	return true;
}


function microsoftKeyPress() {
    if (window.event.keyCode == 13) {
	CalcIt(document.forms[0]);
    }
    return true;

}

// setTimeout("document.forms[0].wt.focus();",1);

// -->