function extractNumber(obj, decimalPlaces, allowNegative)
 
{
 
	var temp = obj.value
	
 
	// avoid changing things if already formatted correctly
 
	var reg0Str = '[0-9]*'
	if (decimalPlaces > 0) {
 
		reg0Str += '\\.?[0-9]{0,' + decimalPlaces + '}'
	} else if (decimalPlaces < 0) {
 
		reg0Str += '\\.?[0-9]*'
	}
 
	reg0Str = allowNegative ? '^-?' + reg0Str : '^' + reg0Str
	reg0Str = reg0Str + '$'
	var reg0 = new RegExp(reg0Str)
	if (reg0.test(temp)) return true
 
 
	// first replace all non numbers
 
	var reg1Str = '[^0-9' + (decimalPlaces != 0 ? '.' : '') + (allowNegative ? '-' : '') + ']'
	var reg1 = new RegExp(reg1Str, 'g')
	temp = temp.replace(reg1, '')
 
 
	if (allowNegative) {
 
		// replace extra negative
 
		var hasNegative = temp.length > 0 && temp.charAt(0) == '-'
		var reg2 = /-/g
		temp = temp.replace(reg2, '')
		if (hasNegative) temp = '-' + temp
	}
 
	
 
	if (decimalPlaces != 0) {
 
		var reg3 = /\./g
		var reg3Array = reg3.exec(temp)
		if (reg3Array != null) {
 
			// keep only first occurrence of .
 
			//  and the number of places specified by decimalPlaces or the entire string if decimalPlaces < 0
 
			var reg3Right = temp.substring(reg3Array.index + reg3Array[0].length)
			reg3Right = reg3Right.replace(reg3, '')
			reg3Right = decimalPlaces > 0 ? reg3Right.substring(0, decimalPlaces) : reg3Right
			temp = temp.substring(0,reg3Array.index) + '.' + reg3Right
		}
 
	}
 
	
 
	obj.value = temp
}
 
function blockNonNumbers(obj, e, allowDecimal, allowNegative)
 
{
 
	var key
	var isCtrl = false
	var keychar
	var reg
		
 
	if(window.event) {
 
		key = e.keyCode
		isCtrl = window.event.ctrlKey
 
	}
 
	else if(e.which) {
 
		key = e.which
		isCtrl = e.ctrlKey
	}
 
	
 
	if (isNaN(key)) return true
	
 
	keychar = String.fromCharCode(key)
	
 
	// check for backspace or delete, or if Ctrl was pressed
 
	if (key == 8 || isCtrl)
 
	{
 
		return true
	}
 
 
 
	reg = /\d/
	var isFirstN = allowNegative ? keychar == '-' && obj.value.indexOf('-') == -1 : false
	var isFirstD = allowDecimal ? keychar == '.' && obj.value.indexOf('.') == -1 : false
	
 
	return isFirstN || isFirstD || reg.test(keychar)
}