function lrn_WriteLogo()
{
	
//扩展频道时，可修改数组channelLogoFiles，增加数组项目便可，数组的键值应该和频道的发布目录一致。

       var channelLogoFiles=new Array();
	   
       channelLogoFiles["media"]="lrnMediaLogo.gif";
       channelLogoFiles["miningmarket"]="lrnMiningmarketLogo.gif"; 
       channelLogoFiles["landmarket"]="lrnLandmarketLogo.gif";
       channelLogoFiles["invest"]="lrnInvestLogo.gif";
       channelLogoFiles["economic"]="lrnEconomicLogo.gif";
       channelLogoFiles["stratage"]="lrnStratageLogo.gif";
       channelLogoFiles["science"]="lrnScienceLogo.gif";
       channelLogoFiles["travel"]="lrnTravelLogo.gif";
       channelLogoFiles["zjtg"]="lrn_zjtgLogo.gif";
       channelLogoFiles["policy"]="lrnPolicyLogo.gif";
       channelLogoFiles["criterion"]="lrnCriterionLogo.gif";
       channelLogoFiles["basicdata"]="lrnBasicdataLogo.gif";
       channelLogoFiles["bookscollection"]="lrnBookscollectionLogo.gif";
       channelLogoFiles["figures"]="lrnFiguresLogo.gif";
       channelLogoFiles["organization"]="lrnOrganizationLogo.gif";
       channelLogoFiles["goldenland"]="lrnGoldenlandLogo.gif";
       channelLogoFiles["dataland"]="lrnDatalandLogo.gif";

       channelLogoFiles["technology"]="lrnScienceExLogo.gif";
       channelLogoFiles["culture"]="lrnCultureLogo.gif";
       
       channelLogoFiles["zygl"]="lrnZYGLLogo.gif";
       channelLogoFiles["specialtopic"]="lrnSpecialtopicLogo.gif";
       
// end for channel logo files
 
	   var defaultLogoURLBase="/lrnSkin/images/logo/";
	   var defaultLogo="lrnLogo.gif";
	
	   var curURL= document.URL;
	   //var curURL="http://www.lrn.cn/mediap/";
	   //document.write(curURL);
	   
	   var urlRegExp=/^http:\/\/[^\/]+\.lrn\.cn\/([^\/]*).*$/gi;
	
	   urlRegExp.exec(curURL);
	   //document.write(RegExp.$1);
	   
	   var logoFile=channelLogoFiles[RegExp.$1];
	   //document.write(logoFile);
	
	   var logoURL;
	   
	   if(logoFile==null|| logoFile=="undefined"||logoFile=="")
	         logoURL=defaultLogoURLBase+defaultLogo;
	   else
	         logoURL=defaultLogoURLBase+logoFile;
	     
	   //document.write(logoURL);
	     
	  var logoImgTag="<img "+"src="+logoURL+" border='0'  width='180' height='64'>";
	  document.write(logoImgTag);
						
}