HP Fortran Programmer's Guide (September 2007)

Compiling and linking

Linking HP Fortran programs

Chapter 2 79

The -l option is order-sensitive: when the linker ﬁnds a reference in an object ﬁle that it

cannot resolve in the default libraries, it searches the libraries (if any) speciﬁed after the ﬁle

on the command line. For example, the following command line tells the linker to look for

unresolved references in the math library as well as the default libraries:

$ f90 prog.f90 -lm

You can also link a library to your program by specifying its name after the name of the source

ﬁle that references it, as follows:

$ f90 prog.f90 /usr/lib/libm.a

This form of the command line is useful for linking libraries that do not conform to the

naming convention required by the -l option or that reside in a directory other than /lib or

/usr/lib. As with the -l option, the library name must follow the name of the source ﬁle that

references it. For example, the following command line links prog.f90 with the library

my_routines, both of which reside in the current working directory:

$ f90 prog.f90 my_routines

If your program calls routines in a library but the linker is unable to resolve the references,

compile with the -Wl,-v option. The f90 command passes -v to the linker, causing it to

process in verbose mode. The verbose information includes:

• The names of the libraries that the linker is searching. This information can conﬁrm that

the linker is searching the correct libraries.

• The names of the object ﬁles selected by the linker to resolve the references. The linker

may have found the same name in another library and resolved the reference there.

Many library-related problems are owing to a misplaced -l on the command line. The -L

option (discussed in “Library search rules” on page 81) is also order-sensitive and can cause