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| 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).
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 |
| 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 |
The following input tells plumed to print the distance between three couple of atoms and compare them with three reference distances.
d1: DISTANCE ATOMS=10,50 d2: DISTANCE ATOMS=1,100 d3: DISTANCE ATOMS=45,75 st: STATS ARG=d1,d2,d3 PARAMETERS=1.5,4.0,2.0 PRINT ARG=d1,d2,d3,st.*
1.8.14