function hideObj(obj) {

    if ( document.getElementById )
    {
        document.getElementById( obj ).style.display = "none";
    }
    else
    if ( document.all )
    {
        document.all[obj].style.display = "none";
    }
}

function showObj(obj) {

  if (document.getElementById)
    {document.getElementById(obj).style.display = "block";}
  else
    {if (document.all)
       {document.all[obj].style.display = "block";}
    }
}

function callToggleUnitTables( theObj ) {
	if ( theObj.value == 'M' )
	{
		hideObj( 'DIVImperialWeight' ) ;
		showObj( 'DIVMetricsWeight' ) ;
		hideObj( 'DIVImperialHeight' ) ;
		showObj( 'DIVMetricsHeight' ) ;
	}
	else
	{
		hideObj( 'DIVMetricsWeight' ) ;
		showObj( 'DIVImperialWeight' ) ;
		hideObj( 'DIVMetricsHeight' ) ;
		showObj( 'DIVImperialHeight' ) ;
	}
}

function hideAll_BMI_Paragraphs( )
{
		hideObj( 'PBMIResultsExtremelyObese' ) ;
		hideObj( 'PBMIResultsVeryObese' ) ;
		hideObj( 'PBMIResultsObese' ) ;
		hideObj( 'PBMIResultsOverweight' ) ;
		hideObj( 'PBMIResultsNormalWeight' ) ;
		hideObj( 'PBMIResultsUnderweight' ) ;
}


function doCalculateBMI( ){

// BMI Calculations:
// 		 metrics: KG / ( M * M ) ... 		 68 \u00F7 (1.65)2 = 24.98
// 		 imperical: ( Pounds / ( Inches * Inches ) * 703 ) ...( [150 \u00F7 (65)2] x 703 = 24.96

		 var doc = document.forms[0] ;

		 if ( doc.bmiUnitType[0].checked )
		 {
		 		 // Metric calculations
		 		 var Kilograms = getFieldValue( doc.bmiKilograms , 'select' ) ;
		 		 var Centimetres = eval( getFieldValue( doc.bmiCentimetres , 'select' ) ) / 100 ;  /* converted to Metres */
		 		 var BMI_prov = ( Kilograms / ( Centimetres * Centimetres ) ) ;
		 }
		 else
		 {
		 		 // Imperial calculations
		 		 var Stones = getFieldValue( doc.bmiStones , 'select' ) ;
		 		 var Pounds = getFieldValue( doc.bmiPounds , 'select' ) ;
		 		 var WeightI = eval( Stones * 14 ) + eval( Pounds ) ;
		 		 
		 		 var Feet = getFieldValue( doc.bmiFeet, 'select' ) ;
		 		 var Inches = getFieldValue( doc.bmiInches , 'select' ) ;
		 		 var HeightI = eval( Feet * 12 ) + eval( Inches ) ;
		 		 		 
		 		 var BMI_prov = ( WeightI  / ( HeightI * HeightI ) ) * 703 ;
		 }

		 var BMI_final = Math.round( BMI_prov * 10 ) / 10 ;
		 doc.bmiResults.value = BMI_final ;

//		document.getElementById('PBMIResults').innerHTML = "result's message appears here"

		hideAll_BMI_Paragraphs( )

		if ( BMI_final < 18.5 )
		{
			showObj( 'PBMIResultsUnderweight' ) ;
		}
		else if ( BMI_final < 25 ) 
		{
			showObj( 'PBMIResultsNormalWeight' ) ;
		}
		else if ( BMI_final < 30 ) 
		{
			showObj( 'PBMIResultsOverweight' ) ;
		}
		else if ( BMI_final < 35 ) 
		{
			showObj( 'PBMIResultsObese' ) ;
		}
		else if ( BMI_final < 40) 
		{
			showObj( 'PBMIResultsVeryObese' ) ;
		}
		else
		{
			showObj( 'PBMIResultsExtremelyObese' ) ;
		}
}