Program: Interp3D
By: Ben Axelrod   


     What is interpolation?  2D interpolation takes two points and draws a 
line through them.  Then it takes the X value you gave it (which is usually 
between these points but does not have to be) and uses this imaginary line 
to find the Y value there.  You could also give it Y to get X.  It doesnt 
mater.  

     3Dimensional interpolation is just three, 2D interpolations.  Of 
course, the 4 points that you give it have to be squared to the X and Y 
axes.  (They have to make a rectangle, not a diamond)  The way that I wrote 
the program, it interpolates across the first two points with the X given, 
then the third and fourth also with the X given.  Basically do not enter 
points 1 and 2 or 3 and 4 so that they have the same X coordinate.  The 
program checks for this and will ask you to enter your points in a different 
order.  

     Here is a bad drawing of what you should have.  The *s are the 4 data 
points that you should enter as numbered.  The O is The Point in question. 
 It does not have to be in side the four points you have, but it is best.

y |
  |     1              2  
  |    *             *
  |
 ---            O  
  |
  |    *             *
  |     3             4
--|-------------|-----------
                           x 


     I have 3 other interpolation programs that you should take a look at.  
If you have any questions or comments, please email me at: bmaxelro@syr.edu
