SELECT CASE (expression) CASE (value-list) ... CASE (value-list) ... ... END SELECTprovides ``parallel" selection control. It offers no increase in semantic power over the IF (``sequential") selection control, but in situations where it fits the problem CASE offers computational advantages over IF because only one expression is evaluated.
The new DO construct is likely to be extremely useful in computational science applications. The reason is that, in order to realize the computational benefits of data parallelism, a great many indexed do loops will be replaced by array operations. The emphasis in the use of loops will therefore shift from processing arrays to indefinite repetition operations such as ``read-test-process" and ``while" repetition. The two new forms of DO construct added in Fortran 90 therefore are:
DO DO WHILE (logical-expr) ... ... IF (logical-expr) EXIT END DO ... END DOIndexed loops may also be terminated with END DO, in which case the loop label is not needed. (Loop labels are permitted, however, in all three forms of DO construct.)