ParsedFunction

Function created by parsing a string

Description

The ParsedFunction function takes a mathematical expression in value. The expression can be a function of time (t) or coordinate (x, y, or z). The expression can include common mathematical functions. Examples include 4e4+1e2*t, sqrt(x*x+y*y+z*z), and if(t\textless=1.0, 0.1*t, (1.0+0.1)*cos(pi/2*(t-1.0)) - 1.0).

Additional variables may be declared in the vars parameter vector. The corresponding vals parameter vector should list the items these variables are bound to. Variables can be bound to:

Constant number literals (for example vars = kB and vals = 8.61733e-5)
A PostProcessor name (providing the value from the PP's last execution)
A Function name (providing an immediate evaluation of the specified function)
A scalar variable name

Further information can be found at the function parser site.

Example Input Syntax

[Functions]
  [./tr_x]
    type = ParsedFunction
    value = sqrt(x^2+y^2)*cos(2*pi/3)
  [../]

  [./tr_y]
    type = ParsedFunction
    value = sqrt(x^2+y^2)*sin(2*pi/3)
  [../]

  [./itr_x]
    type = ParsedFunction
    value = sqrt(x^2+y^2)*cos(0)
  [../]

  [./itr_y]
    type = ParsedFunction
    value = sqrt(x^2+y^2)*sin(0) # Always Zero!
  [../]
[]

/opt/civet/build_0/moose/examples/ex04_bcs/trapezoid.i

[Mesh]
  file = trapezoid.e
  uniform_refine = 1
[]

# Polar to Cartesian
# R = sqrt(x^2 + y^2)
# x = R * cos(theta)
# y = R * sin(theta)
[Functions]
  [./tr_x]
    type = ParsedFunction
    value = sqrt(x^2+y^2)*cos(2*pi/3)
  [../]

  [./tr_y]
    type = ParsedFunction
    value = sqrt(x^2+y^2)*sin(2*pi/3)
  [../]

  [./itr_x]
    type = ParsedFunction
    value = sqrt(x^2+y^2)*cos(0)
  [../]

  [./itr_y]
    type = ParsedFunction
    value = sqrt(x^2+y^2)*sin(0)  # Always Zero!
  [../]
[]

[Variables]
  [./u]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[Kernels]
  [./diff]
    type = Diffusion
    variable = u
  [../]

  # A forcing term near the periodic boundary
  [./forcing]
    type = ExampleGaussContForcing
    variable = u
    x_center = 2
    y_center = -1
    x_spread = 0.25
    y_spread = 0.5
  [../]

  [./dot]
    type = TimeDerivative
    variable = u
  [../]
[]

[BCs]
  [./Periodic]
    [./x]
      primary = 1
      secondary = 4
      transform_func = 'tr_x tr_y'
      inv_transform_func = 'itr_x itr_y'
    [../]
  [../]
[]

[Executioner]
  type = Transient
  dt = 0.5
  num_steps = 6
[]

[Outputs]
  execute_on = 'timestep_end'
  exodus = true
[]

Input Parameters

valueThe user defined function.
C++ Type:FunctionExpression
Options:
Description:The user defined function.

Required Parameters

valsConstant numeric values, postprocessor names, or function names for vars.
C++ Type:std::vector
Options:
Description:Constant numeric values, postprocessor names, or function names for vars.
varsVariables (excluding t,x,y,z) that are bound to the values provided by the corresponding items in the vals vector.
C++ Type:std::vector
Options:
Description:Variables (excluding t,x,y,z) that are bound to the values provided by the corresponding items in the vals vector.

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector
Options:
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Options:
Description:Set the enabled status of the MooseObject.

Advanced Parameters

Description
Example Input Syntax
Input Parameters

Application Usage

Physics and Syntax

Application Development

Framework Development

MOOSEDocs

Infrastructure

Questions

Information and Tools