forked from lijiext/lammps
100 lines
3.2 KiB
HTML
100 lines
3.2 KiB
HTML
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<HTML>
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<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
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</CENTER>
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<HR>
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<H3>next command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>next variables
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</PRE>
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<UL><LI>variables = one or more lower-case single-character variable names
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>next x
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next a t x
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>This command is used with variables defined by the
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<A HREF = "variable.html">variable</A> command. It assigns the next value to the
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variable from the variable's list, so that when $X is subsequently
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substituted for in an input script command, the new value is used. X
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is a single lower-case character from "a" to "z".
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</P>
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<P>All variables in a single next command must be the same style:
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<I>index</I>, <I>loop</I>, or <I>universe</I>. <I>Equal</I>- or <I>world</I>-style variables
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cannot be incremented by a next command.
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</P>
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<P>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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<A HREF = "jump.html">jump</A> command encountered. This enables a loop containing
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a next command to exit.
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</P>
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<P>When the next command is used with <I>index</I>- or <I>loop</I>-style variables,
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the next value is assigned to the variable for all processors. When
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the next command is used with <I>universe</I>-style variables, the next
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value is assigned to whichever processor partition executes the
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command first. All processors in the partition are assigned the same
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value. Running LAMMPS on multiple partitions of processors via the
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"-partition" command-line switch is described in <A HREF = "Section_start.html#2_4">this
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section</A> of the manual. <I>Universe</I>-style
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variables are incremented using the files "tmp.lammps.variable" and
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"tmp.lammps.variable.lock" which you will see in your directory during
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such a LAMMPS run.
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</P>
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<P>Here is an example of running a series of simulations using the next
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command with an <I>index</I>-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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</P>
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<PRE>variable d index run1 run2 run3 run4 run5 run6 run7 run8
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shell cd $d
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read_data data.polymer
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run 10000
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shell cd ..
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clear
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next d
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jump in.polymer
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</PRE>
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<P>If the variable "d" were of style <I>universe</I>, and the same in.polymer
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input script were run on 3 partitions of processors, then the first 3
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simulations would begin, one on each set of processors. Whichever
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partition finished first, it would assign variable "d" the 4th value
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and run another simulation, and so forth until all 8 simulations were
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finished.
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</P>
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<P>Jump and next commands can also be nested to enable multi-level loops.
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For example, this script will run 15 simulations in a double loop.
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</P>
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<P>variable i loop 3
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variable j loop 5
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clear
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...
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read_data data.polymer.$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
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</P>
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<P><B>Restrictions:</B> none
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "jump.html">jump</A>, <A HREF = "include.html">include</A>, <A HREF = "shell.html">shell</A>,
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<A HREF = "variable.html">variable</A>,
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</P>
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<P><B>Default:</B> none
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</P>
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</HTML>
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