STATS

This is part of the function module

Calculates statistical properties of a set of collective variables with respect to a set of reference values.

In particular it calculates and stores as components the sum of the squared deviations, the correlation, the slope and the intercept of a linear fit.

The reference values can be either provided as values using PARAMETERS or using value without derivatives from other actions using PARARG (for example using experimental values from collective variables such as CS2BACKBONE, RDC, NOE, PRE).

Examples

The following input tells plumed to print the distance between three couple of atoms and compare them with three reference distances.

Click on the labels of the actions for more information on what each action computes

d1: DISTANCE 
ATOMS
the pair of atom that we are calculating the distance between. 
=10,50 The DISTANCE action with label d1 calculates a single scalar value
d2: DISTANCE 
ATOMS
the pair of atom that we are calculating the distance between. 
=1,100 The DISTANCE action with label d2 calculates a single scalar value
d3: DISTANCE 
ATOMS
the pair of atom that we are calculating the distance between. 
=45,75 The DISTANCE action with label d3 calculates a single scalar value
st: STATS 
ARG
the input for this action is the scalar output from one or more other actions. 
=d1,d2,d3 
PARAMETERS
the parameters of the arguments in your function 
=1.5,4.0,2.0 The STATS action with label st calculates the following quantities:

 Quantity   
 Description  
st.sqdevsum
the sum of the squared deviations between arguments and parameters
st.corr
the correlation between arguments and parameters
st.slope
the slope of a linear fit between arguments and parameters
st.intercept
the intercept of a linear fit between arguments and parameters


PRINT 
ARG
the input for this action is the scalar output from one or more other actions. 
=d1,d2,d3,st.* The PRINT action with label 

Glossary of keywords and components

Description of components

By default the value of the calculated quantity can be referenced elsewhere in the input file by using the label of the action. Alternatively this Action can be used to calculate the following quantities by employing the keywords listed below. These quantities can be referenced elsewhere in the input by using this Action's label followed by a dot and the name of the quantity required from the list below.

Quantity	Description
sqdevsum	the sum of the squared deviations between arguments and parameters
corr	the correlation between arguments and parameters
slope	the slope of a linear fit between arguments and parameters
intercept	the intercept of a linear fit between arguments and parameters

In addition the following quantities can be calculated by employing the keywords listed below

Quantity	Keyword	Description
sqd	SQDEV	the squared deviations between arguments and parameters

Options

NUMERICAL_DERIVATIVES	( default=off ) calculate the derivatives for these quantities numerically
SQDEVSUM	( default=off ) calculates only SQDEVSUM
SQDEV	( default=off ) calculates and store the SQDEV as components
UPPERDISTS	( default=off ) calculates and store the SQDEV as components
ARG	the input for this action is the scalar output from one or more other actions. The particular scalars that you will use are referenced using the label of the action. If the label appears on its own then it is assumed that the Action calculates a single scalar value. The value of this scalar is thus used as the input to this new action. If * or *.* appears the scalars calculated by all the proceeding actions in the input file are taken. Some actions have multi-component outputs and each component of the output has a specific label. For example a DISTANCE action labelled dist may have three components x, y and z. To take just the x component you should use dist.x, if you wish to take all three components then use dist.*.More information on the referencing of Actions can be found in the section of the manual on the PLUMED Getting Started. Scalar values can also be referenced using POSIX regular expressions as detailed in the section on Regular Expressions. To use this feature you you must compile PLUMED with the appropriate flag. You can use multiple instances of this keyword i.e. ARG1, ARG2, ARG3...
PARARG	the input for this action is the scalar output from one or more other actions without derivatives.
PARAMETERS	the parameters of the arguments in your function