TABLEXN

Format

Example

Definitions

Comments

1. $xi$ must be in either ascending or descending order, but not both.
2. Discontinuities between any two points except the two starting points or two end points. For example, in Figure 1 discontinuities are allowed only between points $x2$ through $x7$ . Also, if $y$ is evaluated at a discontinuity, the average value of $y$ is used. In Figure 1, the value of $y$ at $x=x3$ is $y=\left(y3+y4\right)/2$ .
3. At least one continuation entry must be specified.
4. Any $x$ , $y$ pair may be ignored by placing SKIP in either of the two fields used for that entry.
5. The end of the table is indicated by the existence of ENDT in either of the two fields following the last entry. An error is detected if any continuations follow the entry containing the end-of-table flag ENDT.
6. TABLEXN uses the algorithm:(1)
   $$y=y_T(x)$$
   Where,

   $x$

   Input to the table

   $y$

   Is returned

   The table look-up is performed using interpolation within the table and linear extrapolation outside the table using the two starting or end points (Figure 1). The algorithms used for interpolation or extrapolation is:(2)

   $$y_T(x)=\frac{x_j-x}{x_j-x_i}{y}_i+\frac{x-x_i}{x_j-x_i}{y}_j$$
   Where, $xj$ and $yj$ follow $xi$ and $yi$ .

   
   
   Figure 1. Example of Table Extrapolation and Discontinuity

7. TABLEXN can be directly selected via the MCRV_ID field on the MATFAT entry or referenced on the TIDi fields of the FATMCRV entry.