forked from lijiext/lammps
130 lines
4.4 KiB
Plaintext
130 lines
4.4 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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next command :h3
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[Syntax:]
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next variables :pre
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variables = one or more variable names :ul
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[Examples:]
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next x
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next a t x myTemp :pre
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[Description:]
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This command is used with variables defined by the
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"variable"_variable.html command. It assigns the next value to the
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variable from the list of values defined for that variable by the
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"variable"_variable.html command. Thus when that variable is
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subsequently substituted for in an input script command, the new value
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is used.
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See the "variable"_variable.html command for info on how to define and
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use different kinds of variables in LAMMPS input scripts. If a
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variable name is a single lower-case character from "a" to "z", it can
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be used in an input script command as $a or $z. If it is multiple
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letters, it can be used as $\{myTemp\}.
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If multiple variables are used as arguments to the {next} command,
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then all must be of the same variable style: {index}, {loop}, {file},
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{universe}, or {uloop}. An exception is that {universe}- and
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{uloop}-style variables can be mixed in the same {next} command.
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All the variables specified with the next command are incremented by
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one value from their respective list of values. A {file}-style variable
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reads the next line from its associated file. {String-} or {atom}- or
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{equal}- or {world}-style variables cannot be used with the the next
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command, since they only store a single value.
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When any of the variables in the next command has no more values, a
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flag is set that causes the input script to skip the next
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"jump"_jump.html command encountered. This enables a loop containing
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a next command to exit. As explained in the "variable"_variable.html
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command, the variable that has exhausted its values is also deleted.
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This allows it to be used and re-defined later in the input script.
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{File}-style variables are exhausted when the end-of-file is reached.
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When the next command is used with {index}- or {loop}-style or
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{file}-style variables, the next value is assigned to the variable for
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all processors. When the next command is used with {universe}- or
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{uloop}-style variables, the next value is assigned to whichever
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processor partition executes the command first. All processors in the
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partition are assigned the same value. Running LAMMPS on multiple
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partitions of processors via the "-partition" command-line switch is
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described in "this section"_Section_start.html#start_7 of the manual.
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{Universe}- and {uloop}-style variables are incremented using the
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files "tmp.lammps.variable" and "tmp.lammps.variable.lock" which you
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will see in your directory during such a LAMMPS run.
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Here is an example of running a series of simulations using the next
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command with an {index}-style variable. If this input script is named
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in.polymer, 8 simulations would be run using data files from
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directories run1 thru run8.
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variable d index run1 run2 run3 run4 run5 run6 run7 run8
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shell cd $d
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read_data data.polymer
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run 10000
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shell cd ..
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clear
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next d
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jump in.polymer :pre
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If the variable "d" were of style {universe}, and the same in.polymer
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input script were run on 3 partitions of processors, then the first 3
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simulations would begin, one on each set of processors. Whichever
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partition finished first, it would assign variable "d" the 4th value
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and run another simulation, and so forth until all 8 simulations were
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finished.
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Jump and next commands can also be nested to enable multi-level loops.
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For example, this script will run 15 simulations in a double loop.
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variable i loop 3
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variable j loop 5
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clear
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...
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read_data data.polymer.$i$j
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print Running simulation $i.$j
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run 10000
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next j
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jump in.script
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next i
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jump in.script :pre
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Here is an example of a double loop which uses the "if"_if.html and
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"jump"_jump.html commands to break out of the inner loop when a
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condition is met, then continues iterating thru the outer loop.
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label loopa
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variable a loop 5
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label loopb
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variable b loop 5
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print "A,B = $a,$b"
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run 10000
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if $b > 2 then "jump in.script break"
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next b
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jump in.script loopb
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label break
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variable b delete :pre
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next a
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jump in.script loopa :pre
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[Restrictions:] none
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[Related commands:]
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"jump"_jump.html, "include"_include.html, "shell"_shell.html,
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"variable"_variable.html,
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[Default:] none
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