This example shows how to add inequalities conditions on resulting surface, which a set in areas with other surface values. In this example areas 1,3,5 were used to set greater than or equal to inequality condition with "test_func" surface. Areas 2,4,6 were used to set lower than or equal to inequality condition.
Here is the image of the resulting surface (red colour for areas 1,3,5, green colour for areas 2,4,6):
Pic 1. Surface built from inequalities for regions of other surface
This result was obtained with "examples/surfit/curvs/area_ineq.tcl" script.