Excel add-in with eleven powerful worksheet functions
for 1, 2 and 3 variable lookup and interpolation.
Interpolation modes include: closest-value, linear,
piecewise parabolic or hyperbolic, cubic spline and
polynomial up to 20th order. The functions can also
handle tables containing missing and invalid data.
Includes functions to fit polynomial curves through a
set of X-Y data points and return a table of
polynomial curve coefficients, as well as, determine
the best fit polynomial curve.
In case of an error, TriLookup functions can either
return a standard Excel error code or a detailed text
error message, indicating the nature of the error and
pointing to the cause of it.
Includes online help and example workbooks. Requires
Microsoft Excel 97, 2000, XP or 2003 (Windows) or
Excel 98, 2001 or X (Mac).
TVLOOKUP & TVLKP search a multi column table for the
lookup value in the lookup column and return a value
from the same row of the return column. Can use
interpolation and handle missing values.
THLOOKUP & THLKP search a multi row table for the
lookup value in the lookup row and return a value from
the same column of the return row. Can use
interpolation and handle missing values.
T2LOOKUP & T2LKP search a 2D (X-Y) table for X values
in top row and Y values in left column, and return a
value from the intersecting row and column. Can use
interpolation and handle missing values.
T3LOOKUP & T3LKP search a 3D (X-Y-Z) table for X, Y
and Z values. Return a value V(x,y,z) from the
intersecting row, column and table. Can use
interpolation and handle missing values.
TVPOLYDATA & THPOLYDATA Calculate polynomial curve
coefficients up to a specified order (using the least
squares method) for the X-Y data points given in a
table. Also determine the best fit curve.
TPOLY returns the Y value of a polynomial curve for
given a X value, polynomial order and an array of
polynomial curve coefficients. It can optionally
return the value of a derivative.

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