AIPS NRAO AIPS HELP file for ELSE in 31DEC18



As of Mon Apr 23 13:02:40 2018



HELP SECTION

ELSE
Type:  Pseudoverb
Use:   Used in the IF construction (see IF) to identify a set of
       statements to be executed if a logical condition is false

Grammar:  IF condition THEN statement1;...
          ELSE statementn;...; END
       where condition is a logical statement, either a single
       "logical" variable or a relational condition using =, <=, >=,
       <>, &, ! or a logical variable.  Statementi are AIPS
       statements.  The statements may be separated by semi-colons as
       shown above or they may be on separate lines.  IF...THEN...ELSE
       may be used only in procedures.

       Statementi are AIPS statements.  These statements may not
       have an omittted optional immediate numeric argument.  Such
       statements depend on the POPS stack being empty in the absence
       of the argument.  But the FOR loop uses the stack for the
       'fini' and 'increment' values and so the stack is not empty.
       Thus TVON with no argument will see a non-empty stack and
       assume that it is getting an immediate argument from the stack.
       Use in this case TVON(2**(TVCHAN-1)) inside your loop.

       Verbs of this sort include EHEX, GROFF, GRON, HUEWEDGE,
       IMWEDGE, REHEX, TVOFF, TVON, TVWEDGE.

Examples:  IF A = B THEN PRINT 'A = B'; A=7;
           ELSE PRINT 'A <> B'; A=8; END
           IF A <= B THEN PRINT 'A <= B'; C=9; END

EXPLAIN SECTION


AIPS