AIPS NRAO AIPS HELP file for TO in 31DEC18



As of Mon Apr 23 13:22:03 2018



HELP SECTION

TO
Type:  Verb
Use:   In the FOR loop construction TO is used to seperate the
       starting value for the incrementing variable from the limiting
       value. (See FOR).
Grammar:  FOR variable = start TO fini BY increment
             statement1; statement2;... ; END
       where 'variable' is a scalar variable that will change each
       time through the loop, beginning at 'start', have 'increment'
       added to it each time through the loop (the increment may be
       positive or negative) and will end when the loop has been
       executed with 'variable' greater than or equal to 'fini'.  Note
       that this implies that the loop will be executed at least once
       no matter what the start, fini and increment parameters are.
       If the BY section is omitted, the increment will default to 1.

       Statementi are AIPS statements.  These statements may not
       have an omitted 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:  FOR I = 1 TO 10; SUM = SUM + A(I); END
           FOR I = K+3 TO K BY -1; A(I+1) = A(I); END
       In the first example SUM will be incremented by the
       sum of the first 10 elements in array A.
       The second example will shift the section of array
       A between A(K) and A(K+3) forward 1 element.

EXPLAIN SECTION


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