sorry to disturb again . can anybody tell me wat does line 390 of function forward_pass () under "palign.c" (Clustalw source code) do? wat is "hh"? hh = p + matrix[(int)ia[i]][(int)ib[j]]; __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com