; BY ;--------------------------------------------------------------- ;! gives increment to use in FOR loops in POPS language ;# Verb POPS ;----------------------------------------------------------------------- ;; Copyright (C) 1995 ;; Associated Universities, Inc. Washington DC, USA. ;; ;; This program is free software; you can redistribute it and/or ;; modify it under the terms of the GNU General Public License as ;; published by the Free Software Foundation; either version 2 of ;; the License, or (at your option) any later version. ;; ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; ;; You should have received a copy of the GNU General Public ;; License along with this program; if not, write to the Free ;; Software Foundation, Inc., 675 Massachusetts Ave, Cambridge, ;; MA 02139, USA. ;; ;; Correspondence concerning AIPS should be addressed as follows: ;; Internet email: aipsmail@nrao.edu. ;; Postal address: AIPS Project Office ;; National Radio Astronomy Observatory ;; 520 Edgemont Road ;; Charlottesville, VA 22903-2475 USA ;----------------------------------------------------------------------- ;--------------------------------------------------------------- BY LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC ---------------------------------------------------------------- BY Type: Verb Use: In the FOR loop construction BY is used to signal the value by which to increment the incrementing variable. (See HELP FOR). This value may be negative. The inclusion of BY is optional. If omitted, the increment will default to 1. 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 next loop would be executed with 'variable' greater than (increment > 0; less than with increment < 0) 'fini'. Note 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. Example: FOR I = K+3 TO K BY -1; A(I+1) = A(I); END This example will shift the section of array A between A(K) and A(K+3) forward 1 element. ----------------------------------------------------------------