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There are two options to describe a curve which the mesh approximates:

- program a FORTRAN function, called
**FFRONT**of the following form:FUNCTION FFRONT(I,X,Y)where

- I
- is the reference number of the line (portion of the contour) described, and
- X,Y
- are the space variables.

A typical example of function

**FFRONT**is given below:FUNCTION FFRONT(I,X,Y) IF ( I .EQ. 1) THEN FFRONT = function(X,Y) ELSE IF ( I .EQ. nnn ) FFRONT = ... ELSE IF ... ... END IF END

- make use of the function parser :
A typical example of a function parser, for example the description of the line with reference 1 by a function, is the following:

COURBE01(X,Y) = X*X + (Y-1)*(Y-1) - .125

The first case corresponds to writing a FORTRAN function and linking it at execution. In the second case, the curves are given in a data file, thus avoiding performing a link.