Shortcut: BESSEL

Module	function
Description	Usage
Calculate the value of a Bessel function.
output value	type
the value of the bessel function	scalar/vector

Details and examples

Calculate the value of a Bessel function.

This action can be used to evaluate Bessel functions. This was action is needed because the modified Bessel function of the first kind of order 0 is needed in order to calculate the von-Misses distribution that is used in the implementation of KERNEL. You can thus only use this function to evaluate the modified Bessel function of the first kind of order 0. You can evaluate the value of this Bessel function at $x=1$ by using the following input:

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

cThe CONSTANT action with label c calculates the following quantities:
 Quantity   
 Type   
 Description  
c
scalar
the constant value that was read from the plumed input: CONSTANTCreate a constant value that can be passed to actions This action has hidden defaults. More details VALUEthe single number that you would like to store=1
c: CONSTANTCreate a constant value that can be passed to actions This action uses the defaults shown here. More details VALUEthe single number that you would like to store=1  NROWS the number of rows in your input matrix=0 NCOLS the number of columns in your matrix=0
bThe BESSEL action with label b calculates the following quantities:
 Quantity   
 Type   
 Description  
b
scalar
the value of the bessel function: BESSELCalculate the value of a Bessel function. More details ARGthe values input to this function=c ORDER the order of Bessel function to use=0

Notice that you can also use a vector in the input for this action as illustrated below:

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

cThe CONSTANT action with label c calculates the following quantities:
 Quantity   
 Type   
 Description  
c
vector
the constant value that was read from the plumed input: CONSTANTCreate a constant value that can be passed to actions This action has hidden defaults. More details VALUESthe numbers that are in your constant value=1,1,5,2
c: CONSTANTCreate a constant value that can be passed to actions This action uses the defaults shown here. More details VALUESthe numbers that are in your constant value=1,1,5,2  NROWS the number of rows in your input matrix=0 NCOLS the number of columns in your matrix=0
bThe BESSEL action with label b calculates the following quantities:
 Quantity   
 Type   
 Description  
b
vector
the vector obtained by doing an element-wise application of the value of the bessel function to the input vectors: BESSELCalculate the value of a Bessel function. More details ARGthe values input to this function=c ORDER the order of Bessel function to use=0

The value output by BESSEL in this case is also a vector with three components. These components give the values of the Bessel function at 1.0, 1.5 and 2.0 respectively.

The MASK keyword

As this action only takes one argument in input the MASK keyword action works in the way that is described in the documentation for LESS_THAN. This keyword is only used if the input argument is a vector. You pass to it a vector that contains ones and zeros and that has the same length as the vector that is passed in the input to ARG. If the $i$th element of the vector that was passed in the input to MASK is one then the corresponding element of the output vector is evaluated. If it is equal to zero then that element is not evaluated. Consequently in the example input shown below only the 1st and 4th element of the output vector are evaluated.

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

mThe CONSTANT action with label m calculates the following quantities:
 Quantity   
 Type   
 Description  
m
vector
the constant value that was read from the plumed input: CONSTANTCreate a constant value that can be passed to actions This action has hidden defaults. More details VALUESthe numbers that are in your constant value=1,0,0,1
m: CONSTANTCreate a constant value that can be passed to actions This action uses the defaults shown here. More details VALUESthe numbers that are in your constant value=1,0,0,1  NROWS the number of rows in your input matrix=0 NCOLS the number of columns in your matrix=0
cThe CONSTANT action with label c calculates the following quantities:
 Quantity   
 Type   
 Description  
c
vector
the constant value that was read from the plumed input: CONSTANTCreate a constant value that can be passed to actions This action has hidden defaults. More details VALUESthe numbers that are in your constant value=1,1,5,2
c: CONSTANTCreate a constant value that can be passed to actions This action uses the defaults shown here. More details VALUESthe numbers that are in your constant value=1,1,5,2  NROWS the number of rows in your input matrix=0 NCOLS the number of columns in your matrix=0
bThe BESSEL action with label b calculates the following quantities:
 Quantity   
 Type   
 Description  
b
vector
the vector obtained by doing an element-wise application of the value of the bessel function to the input vectors: BESSELCalculate the value of a Bessel function. More details ARGthe values input to this function=c MASKthe label for a sparse vector/matrix that should be used to determine which elements of the vector/matrix should be computed=m ORDER the order of Bessel function to use=0

Input

The arguments that serve as the input for this action are specified using one or more of the keywords in the following table.

Keyword	Type	Description
ARG	scalar/vector/matrix	the values input to this function
MASK	vector/matrix	the label for a sparse vector/matrix that should be used to determine which elements of the vector/matrix should be computed

Full list of keywords

The following table describes the keywords and options that can be used with this action

Keyword	Type	Default	Description
ARG	input	none	the values input to this function
MASK	input	none	the label for a sparse vector/matrix that should be used to determine which elements of the vector/matrix should be computed
ORDER	compulsory	0	the order of Bessel function to use