Validation test for the block Buildings.Controls.OBC.CDL.Reals.Line.
The input u varies from 0.0 to +2.
The block outputs y = a + b u,
where
u is an input
and the coefficients a and b
are determined so that the line intercepts the two input points
specified by the two points x1 and f1,
and x2 and f2.
The parameters limitBelow and limitAbove
determine whether x1 and x2 are also used
to limit the input u.