Now works with suitesparse on CentOS 5.7.

configure.ac

@@ -33,10 +33,6 @@ AX_LAPACK
 # Checks for header files.
 AC_CHECK_HEADERS([float.h limits.h stddef.h stdlib.h string.h])
 
-AC_CHECK_HEADERS([suitesparse/umfpack.h],
-                 [umfpack_header=yes],
-                 [umfpack_header=no])
-
 # Checks for typedefs, structures, and compiler characteristics.
 AC_HEADER_STDBOOL
 AC_TYPE_SIZE_T
@@ -45,8 +41,17 @@ AC_CHECK_TYPES([ptrdiff_t])
 # Checks for library functions.
 AC_CHECK_FUNCS([floor memmove pow sqrt strchr strtol])
 
+
+# To use UMFPACK, we need the header, and both the AMD and UMFPACK libs.
+AC_CHECK_HEADERS([suitesparse/umfpack.h],
+                 [umfpack_header=yes],
+                 [umfpack_header=no])
+
+AC_SEARCH_LIBS([amd_free], [amd],
+               [amd_lib=yes], [amd_lib=no], [-lm])
+
 AC_SEARCH_LIBS([umfpack_dl_solve], [umfpack],
-               [umfpack_lib=yes], [umfpack_lib=no])
+               [umfpack_lib=yes], [umfpack_lib=no], [-lamd -lm])
 
 AM_CONDITIONAL([UMFPACK],
   [test "x$umfpack_header" != "xno" -a "x$umfpack_lib" != "xno"])