A formula interpreter is embedded in code_saturne, which can be used through the GUI.In order to call the formula editor of the GUI, click on the button: GUI formula button.

This will call a popup window similar to the following one

Definition of a user law for the density

The formula editor is a window with three tabs:

• User expression

  This tab is the formula editor. At the opening of the window only the required symbols are displayed. The syntax colorization shows to the user symbols which are required symbols, functions, or user variables. Each expression uses a C-like syntax and must be closed by a semicolon (;). Compared to a true C syntax, the type of local variables does not need to be defined, as they are assumed to de real-valued.

  Required symbols must be present in the final user law. A syntax checker is used when the user clicks on the OK button.

• Predefined symbols

  There are three types of symbols

  Useful functions

  cos: cosine
  sin: sine
  tan: tangent
  exp: exponential
  sqrt: square root
  log: Napierian logarithm
  acos: arc cosine
  asin: arc sine
  atan(x): arc tangent (arc tangent of x in radians; the return value is in the range [-π/2, π/2])
  atan2(y,x): arc tangent (arc tangent of y/x in radians; the return value is in the range [-π, π])
  cosh: hyperbolic cosine
  sinh: hyperbolic sine
  tanh: hyperbolic tangent
  abs: absolute value
  mod: modulo
  int: floor
  min: minimum
  max: maximum
  
  Useful constants

  pi = 3.14159265358979323846
  e = 2.718281828459045235
  
  Operators and statements

  + - * / ^ ! < > <= >= == != && || while if else

• Examples

  This tab displays examples, which can be copied, pasted, and adapted.