UDF Generation

The Save TableCurve UDF option in the File menu of the Surface-Fit Graph is used to generate UDFs for all built-in equations with 10 or fewer parameters (11 and higher parameter count polynomial and rational equations are excluded).

The generated UDF will consist of the full mathematical equation expression rather than a reference to a built-in function. Note that this generated code will contain only the native mathematical computation. There will be no conditional statements to manage undefined regions. The estimates in the generated UDFs will consist of the values of the actual fitted parameters.

Note that for non-linear equations, generated UDFs will not execute as fast as the built-in functions available via the XY Non-Lin Base function insert help in the User Functions entry dialog. The built-in non-linear functions also contain the conditional code insuring that the functions will return a valid value for all X,Y.

For 2D (XY) Data

For a 2D (XY) fit, you also choose among three XLS file formats: Excel 2000/97, Excel 95, and Excel v4. Excel v4 always writes fixed columns whether or not that data is present; the newer formats write columns only for the data actually present, and use a column order and structure matching TableCurve 2D's automation export. Generated Information is renamed Generated XY Only, writing just the X,Y columns, and the initial X generation always produces a block of 100 points rather than following the surface graph's mesh counts.

The Full Worksheet option can also write the fitted equation directly into the worksheet as a live Excel formula -- no BASIC module needed. Omit writes no formula; Write Using A1 Cell Addressing writes it for specific cells; Write Using R1C1 Cell Addressing writes it with relative row-column addresses (used by the automation facility when multiple export streams share a sheet). No formula is generated for Chebyshev or Fourier Series equations, since they can't be expressed as a single-line formula, and for Excel 95 and Excel v4, no formula is generated for equations with more than 11 coefficients, due to a formula length limit in those Excel versions -- for those cases, use the BASIC module approach via Code Generation instead, which handles every equation including Chebyshev and Fourier Series.