II am using Plot3D to visualise a complicated surface. The parameters are c and t (t is an angle in degrees).The surface consists of recurring peaks. The highest peak occurs at tan t = 0,5 and c=- 0. So far so good. Bur this highest peak should be 200 units high. Yet it appears much shorter. Why? i have (I think) suppressed the check for machine underflow. Please help. Many thanks. Bob Frenkel. Email is frenkelfamily@hotmail.com One attachment