php生成缩略图的更能，遇到点有关问题

php生成缩略图的更能，遇到点问题，请教各位
想实现一个上传图片并生成缩略图的功能，从网上找了断代码，也成功了。
想一次生成两张――一张大缩略图，一张小缩略图，结果就提是下面的代码：

Notice: Undefined variable: RESIZEWIDTH in D:\WWW\qiangyuan\up.php on line 17
Notice: Undefined variable: RESIZEWIDTH in D:\WWW\qiangyuan\up.php on line 23



源程序代码如下：

//****************************************
//生成缩略图========================================

function ResizeImage($im,$maxwidth,$maxheight,$name){ 
$width = imagesx($im); 
$height = imagesy($im); 
if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){ 
if($maxwidth && $width > $maxwidth){ 
$widthratio = $maxwidth/$width; 
$RESIZEWIDTH=true; 
} 
if($maxheight && $height > $maxheight){ 
$heightratio = $maxheight/$height; 
$RESIZEHEIGHT=true; 
} 
if($RESIZEWIDTH && $RESIZEHEIGHT){ 
if($widthratio $ratio = $widthratio; 
}else{ 
$ratio = $heightratio; 
} 
}elseif($RESIZEWIDTH){ 
$ratio = $widthratio; 
}elseif($RESIZEHEIGHT){ 
$ratio = $heightratio; 
} 
$newwidth = $width * $ratio; 
$newheight = $height * $ratio; 
if(function_exists("imagecopyresampled")){ 
$newim = imagecreatetruecolor($newwidth, $newheight); 
imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); 
}else{ 
$newim = imagecreate($newwidth, $newheight); 
imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); 
} 
ImageJpeg ($newim,$name . ".jpg"); 
ImageDestroy ($newim); 
}else{ 
ImageJpeg ($im,$name . ".jpg"); 
} 
}

$FILENAME="product/min/".date("YmdHis"); //小图片文件名
$RESIZEWIDTH=150; // 生成图片的宽度
$RESIZEHEIGHT=113; // 生成图片的高度 



if(isset($_FILES['image']['size'])){ 
if($_FILES['image']['type'] == "image/pjpeg"){ 
$im = imagecreatefromjpeg($_FILES['image']['tmp_name']); 
}elseif($_FILES['image']['type'] == "image/x-png"){ 
$im = imagecreatefrompng($_FILES['image']['tmp_name']); 
}elseif($_FILES['image']['type'] == "image/gif"){ 
$im = imagecreatefromgif($_FILES['image']['tmp_name']); 
} 


if($im){ 
if(file_exists("$FILENAME.jpg")){ 
unlink("$FILENAME.jpg"); 
} 

ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME); //生成小图
ResizeImage($im,600,450,"product/max/".date("YmdHis")); //生成大图
ImageDestroy ($im); 
} 
} 

//****************************************
?>