To Find Path Of SQL Log File

declare @dir nvarchar(4000) 

exec master.dbo.xp_instance_regread N'HKEY_LOCAL_MACHINE',N'Software\Microsoft\MSSQLServer\MSSQLServer',N'SQLArg1', @dir output, 'no_output' 

if @dir is null 
begin
exec master.dbo.xp_instance_regread N'HKEY_LOCAL_MACHINE',N'Software\Microsoft\MSSQLServer\Setup',N'SQLDataRoot', @dir output, 'no_output'
select @dir = @dir + N'\LOG'
end

select @dir