Using Lua functions for space time functions

  1. TreElm Overview
  2. Feature Overview
  3. Variable System
  4. Using Lua functions for space time functions

In this section we introduce the use on how to define variables with Lua functions.

Lua functions are defined inside the code like this:

function velocityX(x,y,z,t)
  velX = math.sin(x) * math.cos(y) * math.cos(z) * math.exp(-t/tD)
  return velX
end

To use them for the simulation run you need to add it to the variable table.

variable = {
  {
    name = 'lua_fun_1',
    ncomponents = 1
    vartype = 'st_fun',
    st_fun = velocityX
  },
  -- or in this way:
  {
    name = 'lua_fun_2',
    ncomponents = 1
    vartype = 'st_fun',
    st_fun = {
      fun = velocityX
    }
  },
  -- or for a special shape:
  {
    name = 'lua_fun_3',
    ncomponents = 1
    vartype = 'st_fun',
    st_fun = {
      fun = velocityX
      shape = { 
        -- example: line
        kind = 'canoND', 
        object = {
          origin = {0.0,0.0,0.0}, 
          vec = {1.0,0.0,0.0}, 
        } -- object
      } -- shape
    } -- st_fun
  },
}

A combination of a spatial Lua function and a temporal Lua function is shown below.

a = 10.5

function x(t)
  y = math.cos(a*t)
  return y
end

function lua_fun(x,y,z)
  res = x*y + x*z*a
  return res
end

variable = {
  {
    name = 'two_lua',
    ncomponents = 1,
    vartype = st_fun,
    st_fun = {
      kind = 'combined',
      spatial = lua_fun,
      temporal = x
    }
  }
}