Predefined Elements

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Predefined Elements

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The problem descriptor language predefines the following element:

 

PI

3.14159265358979

 

For Cartesian coordinates in which 'R' is not specified as a coordinate name or a defined name, the problem descriptor language predefines the following elements:

 

R          

R=SQRT(x^2 + y^2)

 

radius vector length in 2D

           

R=SQRT(x^2 + y^2 + z^2)

 

radius vector length in 3D

 

 

 

THETA      

THETA = ARCTAN(y/x)

 

azimuthal angle in 2D or 3D

 

Note: If "R" or "Theta" appear on the left side of a definition before any use in an expression, then the new definition will become the meaning of the name, and the predefined meaning will be hidden.

 

In staged problems where "STAGES = integer" is declared in the SELECT section,

 

STAGE            

an internally declared index which increments from 1 to integer.

 

In modal analysis (eigenvalue and eigenfunction) problems where "MODES = integer" is declared in the SELECT section,

 

LAMBDA

an internally declared name which represents the various eigenvalues.

 

In time-dependent problems, the current timestep interval is available:

 

DELTAT

an internally declared name which returns the size of the current timestep.