The IF..THEN..ELSE construct is almost identical to the FORTRAN feature, both in syntax and effect.
The only differences are the limitations on the form of the <logical expression> (see below) and that the construct ELSEIF is not supported.
IF constructs can be nested to a maximum depth of 20 and inter- leaved freely with DO loops and other "flow-control" features.
The syntax of the block IF is:
IF <logical expression> THEN + <PIL statements 1> ELSE + <PIL statements 2> ENDIF
For example: IF(NX.GT.1) THEN + SOLVE(U1) -----> PIL statement ELSE + SOLVE(V1) -----> PIL statement ENDIF
The <logical expression> has a syntax and capability very similar to the corresponding FORTRAN construct, with the following differences:
IFs can be nested to a maximum depth of 20.