It has been shown by Friis-Christensen and Lassen (1991) that there is a close correspondence in the behaviour of the mean northern hemisphere air temperature and the length of the sunspot cycle, over the period 1861-1990. ... In this paper we extend the comparison between sunspot cycle length and temperature back to the late 18th century using data accumulated at Armagh Observatory since 1795. ...

Routines can now be called with keyword arguments and can use default arguments, that means that some arguments can be given with keywords instead of position and some do not have to be given at all, in which case a standard or default value is used. ... IMPLICIT NONE INTERFACE SUBROUTINE SOLVE (A, B, N) INTEGER, INTENT (IN) : : N REAL, INTENT(OUT) : : A REAL, INTENT(IN), OPTIONAL : : B END SUBROUTINE SOLVE END INTERFACE REAL X ! ... You will use keyword arguments and default arguments so that . ...