** File: TPSht_01.hlp
** Index: 40

** More Sheet View Help
   :: Interpolation commands
   :: Fitting commands


Û  Interpolation

    The Math | Interpolate menu item
contains a pop-up menu which contains the
data interpolation commands.

Û  Polynomial

    This command interpolates the selected
  X-Y columns by a polynomial of degree
  n-1, where n is the number of valid data
  points of X-Y columns.

Û  Rational

    This command interpolates the selected
    X-Y columns by a rational function of
    degree K-1, where K is the number of
    valid data points of X-Y columns.

Û  Natural Spline

    This command interpolates data using
  a natural cubic polynomials between each
  successive pair of nodes.

Û  Clamped Spline

    This command interpolates the selected
  X-Y columns by a clamped cubic spline.
  The boundary conditions are given in a
  way such that the third derivatives are
  continuous.

Û  Stineman

    This command interpolates the selected
    X-Y columns by a Stineman function.
    The Stineman function consists of
    piecewise diagonal rational functions
    of order 3 (i.e. the degree of
    numerator polynomial is 2 and the
    degree of denominator polynomial is 1).
    These rational functions are to have
    continuity up to first derivative.


Û  Fitting

    This menu item contains six fitting
commands.  The first five commands are
linear in terms of the parameters
appearing in the pre-defined function form.
The last command is for user-defined
non-linear parameter fitting.

Û  Line: a*x+b

    This command fits the selected x-y
  data by a straight line.

Û  Power: a*x^b

    This command fits the selected x-y
  data by a power function.

Û  Exp: a*exp(b*x)

    This command fits the selected x-y
  data by a mono-exponential function.

Û  Polynomial

    This command fits the selected x-y
  data by a polynomial

Û  Spline

    This command fits the selected x-y
  data by a natural cubic spline.

Û  User Defined

    This command performs non-linear
  curve fitting.  It displays the Fitting
  dialog box. In this dialog box, you can
  type in a model or load/save a model
  from/to disk.  The model file format
  are described in Section 6.4.2.  In the
  model equations, you can have up to 10
  independent variables, 10 dependent
  variables, and 10 parameters.  This means
  you can do 3D curve fitting easily with
  the Math | Fitting - User-Define command.

  See TpSht_09.hlp (Index: 48) on TechPlot's
model equation convention.
