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
surfit: gridding and contouring software.