General transforms

They are defined by formulas, using the command transform_gen, and can act on points, lines, circles and polygons, using the command act. They are given by strings defining formulas for the $x$ and $y$ coordinates, depending on the variables x, y :

 - funct -> transform_gen Tgen x*cos(x*y-exp(y))  x*x+y*y

It is also possible to perform the action of a general transform on a line segment defined by its end points, using the command act_s. The result is stored in a polygon :

 - funct -> point A
 - funct -> point B
 - funct -> coord A 1 2
 - funct -> coord B -2 5
 - funct -> polyg Pol 250
 - funct -> act_s T A B Pol