# Help System (web edition)

```INTERP L1,L2,L3,L4,K
where K is a label of a mask line of the form
XXXXX   XXXX  YY.YYY  XX   YYY.YY
interpolates columns denoted by Y masks by linear regression analysis
using X columns as regressors. If there are no X columns or only one
X column appears, the Y columns are interpolated by polynomial regres-
sion. In this case the degree m of the polynomial is given by the
specification DEGREE=m. Default is DEGREE=1.
The source data with complete X and Y values is given on lines L1-L2.
The interpolated (and extrapolated) Y values will be computed on
lines L3-L4 using given X values on the same lines.
In polynomial regression without X columns, L-L1+1 where L is the
current line number, is the basic regressor. In this case it is typical
that L3=L2+1.
Examples on the next page!

57 *INTERP A,B,C,D,E
58 E  XX  XX    YYY.Y  YYY.YY
59 A  10   5     15.5   25
60 *   0   3      3.5    3
61 *   7   4     11.5   18
62 B   2  -5     -2.5   -1
63 C   7   4     11.5   18.00
64 *   3   3      6.5    9.00
65 D  11   3     14.5   25.00
66 *.............................................................................................
67 *INTERP CUR+2,CUR+4,CUR+5,CUR+7,CUR+1  / DEGREE=2
68 *      YYY
69 *        1
70 *        4
71 *        9
72 *       16
73 *       25
74 *       36