var theObj;
if(document.all){
      if(typeof obj=="string"){
            return document.all(obj);
      }else{
            return obj.style;
        }
 }
        if(document.getElementById){
                if(typeof obj=="string"){
                        return document.getElementById(obj);
                }else{
                        return obj.style;
                }  
        }
        return null;
} // function gObj

function isInteger(value) {
        if ((undefined === value) || (null === value)) {
                return false;
        }
        return value % 1 == 0;
} // function is_Integer

function showquickmsg(inStr, isError){
        if (isError) inStr = "<font color=red>" + inStr + "</font>";
                gObj("coutput").innerHTML = inStr;
} // function showquickmsg
        
function bodycompcalc() {

        showquickmsg("validating...",true);

        weight_lbs = gObj("cpound").value;
        start_bf_pct = gObj("cbeforebfpct").value;
        start_sm_pct = gObj("cbeforesmpct").value;
        end_bf_pct = gObj("cendbfpct").value;
        end_sm_pct = gObj("cendsmpct").value;

        if ( (!isInteger(weight_lbs)) || (weight_lbs < 1) || (weight_lbs > 999) ) {
                showquickmsg("weight must be an integer between 1 and 999",true);
                return;
        } // weight_lbs fails validation.

        if ( (!isInteger(start_bf_pct)) || (start_bf_pct < 1) || (start_bf_pct > 100) ) {
                showquickmsg("Starting Body Fat Percentage must be an integer between 1 and 100",true);
                return;
        } // start_bf_pct fails validation

        if ( (!isInteger(start_sm_pct)) || (start_sm_pct < 1) || (start_sm_pct > 100) ) {
                showquickmsg("Starting Skeletal Muscle Percentage must be an integer between 1 and 100",true);
                return;
        } // start_sm_pct fails validation.

        if ( (!isInteger(end_bf_pct)) || (end_bf_pct < 1) || (end_bf_pct > 100) ) {
                showquickmsg("Ending Body Fat Percentage must be an integer between 1 and 100",true);
                return;
        } // end_bf_pct fails validation.

        if ( (!isInteger(end_sm_pct)) || (end_sm_pct < 1) || (end_sm_pct > 100) ) {
                showquickmsg("Ending Skeletal Muscle Percentage must be an integer between 1 and 100",true);
                return;
        } // end_sm_pct fails validation.

        showquickmsg("calculating...",true);

        weight_kg = weight_lbs * 0.453592;
        RMR_start_bf = weight_kg * ( start_bf_pct / 100 )  *  4.5;
        RMR_start_sm = weight_kg * ( start_sm_pct / 100 )  * 13.0;
        RMR_end_bf   = weight_kg * ( end_bf_pct   / 100 )  *  4.5;
        RMR_end_sm   = weight_kg * ( end_sm_pct   / 100 )  * 13.0;
        deltaBodyfat        = end_bf_pct - start_bf_pct;
        deltaSkeletalMuscle = end_sm_pct - start_sm_pct;
        NetCaloricDiff = Math.round((RMR_end_bf + RMR_end_sm) - (RMR_start_bf + RMR_start_sm));

        var outMsg = "A change of " + deltaBodyfat.toString();
                outMsg += "% to body fat and " + deltaSkeletalMuscle.toString() ;
                outMsg += "% to skeletal muscle changes caloric requirements by ";
                outMsg += NetCaloricDiff.toString() + " calories/day.";

        showquickmsg( outMsg , false);

} // function bodycompcalc