void view (xvu, yvu, zvu) D3PLT.C Level 1
 
float xvu The x position of viewpoint in units of graf3d().
float yvu The y position of viewpoint in units of graf3d().
float zvu The z position of viewpoint in units of graf3d().
 
To obtain a perspective view, you must specify the position (viewpoint) of the observer. The viewpoint must be outside the workbox. If it is very close, there will be a lot of perspective distortion. If it is far off, perspective distortion 
will be eliminated. The plot will not shrink as the distance of the viewpoint is increased unless sclfix() has been called. The viewpoint should be above the x-y plane or the labels will be backwards. Do not use with vuangl() or vuabs(). One corner of the x-y plane must be the closest point to the viewpoint. 

To view the surface from below, negate the values produced by zfun(), or the values loaded in zmat, and view the 
surface from above. Be sure that your call to graf3d() reflects the negated data values.