PiecewiseConstant

Defines data using a set of x-y data pairs

Description

The PiecewiseConstant function defines the data using a set of x-y data pairs. Instead of linearly interpolating between the values, however, the PiecewiseConstant function is constant when the abscissa is between the values provided by the user. The direction parameter controls whether the function takes the value of the abscissa of the user-provided point to the right or left value at which the function is evaluated. Also available is right_inclusive and left_inclusive options, which will return the value of the function at the specified abscissa.

Example Input Syntax

[Functions]
  [a]
    type = PiecewiseConstant
    xy_data = '0.5 0.1
               1.0 0.2
               1.5 0.1'
    direction = left
  []
  [b]
    type = PiecewiseConstant
    x = '0.5 1.0 1.5'
    y = '0.1 0.2 0.1'
    direction = right
  []
  [c]
    type = PiecewiseConstant
    data_file = pc.csv
    direction = left
    format = columns
  []
  [d]
    type = PiecewiseConstant
    data_file = pc.csv
    direction = right
    format = columns
  []
[]

Input Parameters

axisThe axis used (x, y, or z) if this is to be a function of position
C++ Type:MooseEnum
Unit:(no unit assumed)
Options:x, y, z
Controllable:No
Description:The axis used (x, y, or z) if this is to be a function of position
directionLEFTDirection to look to find value: LEFT RIGHT LEFT_INCLUSIVE RIGHT_INCLUSIVE
Default:LEFT
C++ Type:MooseEnum
Unit:(no unit assumed)
Options:LEFT, RIGHT, LEFT_INCLUSIVE, RIGHT_INCLUSIVE
Controllable:No
Description:Direction to look to find value: LEFT RIGHT LEFT_INCLUSIVE RIGHT_INCLUSIVE
scale_factor1Scale factor to be applied to the ordinate values
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:Yes
Description:Scale factor to be applied to the ordinate values

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Set the enabled status of the MooseObject.

Advanced Parameters

data_fileFile holding CSV data
C++ Type:FileName
Unit:(no unit assumed)
Controllable:No
Description:File holding CSV data
formatrowsFormat of csv data file that is in either in columns or rows
Default:rows
C++ Type:MooseEnum
Unit:(no unit assumed)
Options:columns, rows
Controllable:No
Description:Format of csv data file that is in either in columns or rows
x_index_in_file0The abscissa index in the data file
Default:0
C++ Type:unsigned int
Unit:(no unit assumed)
Controllable:No
Description:The abscissa index in the data file
x_titleThe title of the column/row containing the x data in the data file
C++ Type:std::string
Unit:(no unit assumed)
Controllable:No
Description:The title of the column/row containing the x data in the data file
xy_in_file_onlyTrueIf the data file only contains abscissa and ordinate data
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:If the data file only contains abscissa and ordinate data
y_index_in_file1The ordinate index in the data file
Default:1
C++ Type:unsigned int
Unit:(no unit assumed)
Controllable:No
Description:The ordinate index in the data file
y_titleThe title of the column/row containing the y data in the data file
C++ Type:std::string
Unit:(no unit assumed)
Controllable:No
Description:The title of the column/row containing the y data in the data file

Data From Csv File Parameters

json_uoJSONFileReader holding the data
C++ Type:UserObjectName
Unit:(no unit assumed)
Controllable:No
Description:JSONFileReader holding the data
x_keysOrdered vector of keys in the JSON tree to obtain the abscissa
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
Controllable:No
Description:Ordered vector of keys in the JSON tree to obtain the abscissa
y_keysOrdered vector of keys in the JSON tree to obtain the ordinate
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
Controllable:No
Description:Ordered vector of keys in the JSON tree to obtain the ordinate

Data From Json Parameters

xThe abscissa values
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:The abscissa values
xy_dataAll function data, supplied in abscissa, ordinate pairs
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:All function data, supplied in abscissa, ordinate pairs
yThe ordinate values
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:The ordinate values

Data From Input File Parameters

(moose/test/tests/functions/piecewise_constant/piecewise_constant.i)

# This tests the PiecewiseConstant function.
# There are four variables and four functions: a,b,c, and d.  The diffusion equation is "solved"
# for each of these variables with a boundary condition of type FunctionDirichletBC applied to a boundary
# (i.e. node set) that includes every node in the element, so the solution is the boundary condition defined by the function.
# Each boundary condition uses a function of type PiecewiseConstant.
#
# The value of the variables should correspond to the function.

[Mesh]
  file = cube.e
  # This problem only has 1 element, so using DistributedMesh in parallel
  # isn't really an option, and we don't care that much about DistributedMesh
  # in serial.
  parallel_type = replicated
[]

[Variables]
  [aVar]
    order = FIRST
    family = LAGRANGE
    initial_condition = 0.1
  []
  [bVar]
    order = FIRST
    family = LAGRANGE
    initial_condition = 0.1
  []
  [cVar]
    order = FIRST
    family = LAGRANGE
    initial_condition = 0.1
  []
  [dVar]
    order = FIRST
    family = LAGRANGE
    initial_condition = 0.1
  []
[]

[Functions]
  [a]
    type = PiecewiseConstant
    xy_data = '0.5 0.1
               1.0 0.2
               1.5 0.1'
    direction = left
  []
  [b]
    type = PiecewiseConstant
    x = '0.5 1.0 1.5'
    y = '0.1 0.2 0.1'
    direction = right
  []
  [c]
    type = PiecewiseConstant
    data_file = pc.csv
    direction = left
    format = columns
  []
  [d]
    type = PiecewiseConstant
    data_file = pc.csv
    direction = right
    format = columns
  []
[]

[Kernels]
  [diffa]
    type = Diffusion
    variable = aVar
  []
  [diffb]
    type = Diffusion
    variable = bVar
  []
  [diffc]
    type = Diffusion
    variable = cVar
  []
  [diffd]
    type = Diffusion
    variable = dVar
  []
[]

[BCs]
  [a]
    type = FunctionDirichletBC
    variable = aVar
    boundary = '1'
    function = a
  []
  [b]
    type = FunctionDirichletBC
    variable = bVar
    boundary = '1'
    function = b
  []
  [c]
    type = FunctionDirichletBC
    variable = cVar
    boundary = '1'
    function = c
  []
  [d]
    type = FunctionDirichletBC
    variable = dVar
    boundary = '1'
    function = d
  []
[]

[Executioner]
  type = Transient
  dt = 0.2
  end_time = 3
  nl_rel_tol = 1e-12
[]

[Outputs]
  exodus = true
[]

Description
Example Input Syntax
Input Parameters