Please go to api/error.finc for the API documentation.

The error handling subroutines are available from Fortran, with exception of the macros GSL_ERROR and GSL_ERROR_VAL. A user-defined error handler can be defined either in C or using a Fortran function with the bind(c) attribute. Here is the description of the required interface:

 subroutine errhand(reason, file, line, errno) bind(c)
    type(c_ptr), value :: reason, file
    integer(c_int), value :: line, errno
 end subroutine errhand
 

An object of type fgsl_error_handler_t is returned by the constructor fgsl_error_handler_init(errhand), which takes a subroutine with the interface described above as its argument. The subroutine fgsl_error(reason, file, line, errno) works in an analogous manner as the C version. If the Fortran preprocessor is supported, it should be possible to use the macros __FILE__ and __LINE__ in the above call. Once not needed any more, the error handler object can be deallocated by calling the subroutine fgsl_error_handler_free with itself as its only argument. Note that the function fgsl_strerror returns a string of length fgsl_strmax.