This interpolation software relies on the gensub record (written by
Andy Foster), a copy of which is included in synApps, built in the
std/stdApp/src directory.

The following fields of the gensub record have the following functions
in this software:

A    independent variable array.  The values needn't be equally spaced.
N0A  allocated length of A array
B    y1(A) array
N0B  allocated length of B array
C    y2(A) array
N0C  allocated length of C array
D    new value of independent variable for which y1(D) and y2(D) are desired
E    number of values actually used in A, B, C arrays
F    kind of interpolation to be done:
         0,1 : linear interpolation
         > 1 : polynomial of order F

VALB Interpolated value y1(D)
VALC Interpolated value y2(D)
VALF low limit for D
VALG high limit for D

Here's how you use it:

Load A, B, C arrays such that B[i] = y1(A[i]) and C[i] = y2(A[i]),
where y1 and y2 are the functions you want to interpolate.  You can
do this by editing the file interp.load, and using BURT to load it, or
by editing the file interp.sav and using autosave/restore to load it.
The supplied interp.adl file expects interp.load to be located in
../burt, relative to the directory in which medm was started.  You
could also do it by hand.
However you load the arrays, make sure you do all of the following:
    1) load the number of points in the A, B, C arrays into E
    2) load arrays into A, B, and C
    3) cause the record to process, so that limits will be calculated
       and written to $(P)interp_x.DRVL, $(P)interp_x.DRVL.

The supplied database adds a sort of user interface to the software
described above.  The user writes to $(P)interp_x, and the database
sends this (limit-checked) value to the gensub record, which interpolates
and writes to $(P)interp_y1 and $(P)interp_y2.  If the user has specified
output-link fields $(P)interp_y1.OUT or $(P)interp_y2.OUT, then the
values will be written to the PV's named in those links.

Tim Mooney 7/28/2004