2#if defined TANGENT && defined BIOLOGY
6************************************************************************
8** this routine computes the tangent linear source and sink terms for **
9** the selected biology model. **
11************************************************************************
14# if defined BIO_FENNEL
18# elif defined NPZD_FRANKS
19# include <tl_npzd_Franks.h>
20# elif defined NPZD_IRON
21# include <tl_npzd_iron.h>
22# elif defined NPZD_POWELL
23# include <tl_npzd_Powell.h>