</H3>

<P><B>Syntax:</B>

</P>

<PRE>compute ID group-ID style arg mode input1 input2 ... keyword args ... 

<PRE>compute ID group-ID style arg mode input1 input2 ... 

</PRE>

<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command 

  f_ID[I] = Ith column of array calculated by a fix with ID

  v_name = per-atom vector calculated by an atom-style variable with name 

</PRE>

<LI>zero or more keyword/args pairs may be appended 

<LI>keyword = <I>replace</I> 

<PRE>  <I>replace</I> args = vec1 vec2

    vec1 = reduced value from this input vector will be replaced

    vec2 = replace it with vec1[N] where N is index of max/min value from vec2 

</PRE>

</UL>

<P><B>Examples:</B>

<PRE>compute 1 all reduce sum c_force

compute 1 all reduce/region subbox sum c_force

compute 2 all reduce min c_press<B>2</B> f_ave v_myKE 

compute 3 fluid reduce max c_index<B>1</B> c_index<B>2</B> c_dist replace 1 3 replace 2 3 

</PRE>

<P><B>Description:</B>

</P>

this is a very general means of generating per-atom quantities to

reduce.

</P>

<HR>

<P>If the <I>replace</I> keyword is used, two indices <I>vec1</I> and <I>vec2</I> are

specified, where each index ranges from 1 to the # of input values.

The replace keyword can only be used if the <I>mode</I> is <I>min</I> or <I>max</I>.

It works as follows.  A min/max is computed as usual on the <I>vec2</I>

input vector.  The index N of that value within <I>vec2</I> is also stored.

Then, instead of performing a min/max on the <I>vec1</I> input vector, the

stored index is used to select the Nth element of the <I>vec1</I> vector.

</P>

<P>Thus, for example, if you wish to use this compute to find the bond

with maximum stretch, you can do it as follows:

</P>

<PRE>compute 1 all property/local batom1 batom2

compute	2 all bond/local dist

compute	3 all reduce max c_1[1] c_1[2] c_2 replace 1 3 replace 2 3

thermo_style custom step temp c_3[1] c_3[2] c_3[3] 

</PRE>

<P>The first two input values in the compute reduce command are vectors

with the IDs of the 2 atoms in each bond, using the <A HREF = "compute_property_local.html">compute

property/local</A> command.  The last input

value is bond distance, using the <A HREF = "compute_bond_local.html">compute

bond/local</A> command.  Instead of taking the

max of the two atom ID vectors, which does not yield useful

information in this context, the <I>replace</I> keywords will extract the

atom IDs for the two atoms in the bond of maximum stretch.  These atom

IDs and the bond stretch will be printed with thermodynamic output.

</P>

<HR>

<P>If a single input is specified this compute produces a global scalar

value.  If multiple inputs are specified, this compute produces a

vector of global values, the length of which is equal to the number of

[Syntax:]

compute ID group-ID style arg mode input1 input2 ... keyword args ... :pre

compute ID group-ID style arg mode input1 input2 ... :pre

ID, group-ID are documented in "compute"_compute.html command :ulb,l

style = {reduce} or {reduce/region} :l

  f_ID = vector calculated by a fix with ID

  f_ID\[I\] = Ith column of array calculated by a fix with ID

  v_name = per-atom vector calculated by an atom-style variable with name :pre

zero or more keyword/args pairs may be appended :l

keyword = {replace} :l

  {replace} args = vec1 vec2

    vec1 = reduced value from this input vector will be replaced

    vec2 = replace it with vec1\[N\] where N is index of max/min value from vec2 :pre

:ule

[Examples:]

compute 1 all reduce sum c_force

compute 1 all reduce/region subbox sum c_force

compute 2 all reduce min c_press[2] f_ave v_myKE

compute 3 fluid reduce max c_index[1] c_index[2] c_dist replace 1 3 replace 2 3 :pre

compute 2 all reduce min c_press[2] f_ave v_myKE :pre

[Description:]

this is a very general means of generating per-atom quantities to

reduce.

:line

If the {replace} keyword is used, two indices {vec1} and {vec2} are

specified, where each index ranges from 1 to the # of input values.

The replace keyword can only be used if the {mode} is {min} or {max}.

It works as follows.  A min/max is computed as usual on the {vec2}

input vector.  The index N of that value within {vec2} is also stored.

Then, instead of performing a min/max on the {vec1} input vector, the

stored index is used to select the Nth element of the {vec1} vector.

Thus, for example, if you wish to use this compute to find the bond

with maximum stretch, you can do it as follows:

compute 1 all property/local batom1 batom2

compute	2 all bond/local dist

compute	3 all reduce max c_1\[1\] c_1\[2\] c_2 replace 1 3 replace 2 3

thermo_style custom step temp c_3\[1\] c_3\[2\] c_3\[3\] :pre

The first two input values in the compute reduce command are vectors

with the IDs of the 2 atoms in each bond, using the "compute

property/local"_compute_property_local.html command.  The last input

value is bond distance, using the "compute

bond/local"_compute_bond_local.html command.  Instead of taking the

max of the two atom ID vectors, which does not yield useful

information in this context, the {replace} keywords will extract the

atom IDs for the two atoms in the bond of maximum stretch.  These atom

IDs and the bond stretch will be printed with thermodynamic output.

:line

If a single input is specified this compute produces a global scalar

value.  If multiple inputs are specified, this compute produces a

vector of global values, the length of which is equal to the number of