Linear Interpolation (2D)

The following example illustrates linear interpolation in characteristic maps (two-dimensional tables). It uses a table LLpr2 that has the following values:

y \ x	0.0	1.0	8.0	15.0
1.0	-5.0	-3.0	0.0	1.0
3.0	0.0	1.0	4.0	6.0
5.0	8.0	5.0	4.0	4.0

As with characteristic lines, the method getAt (Xvalue,Yvalue) contains everything that is needed for the evaluation of characteristic maps. Linear interpolation for this example works as follows:

tmpVal = LLpr2.getAt(8,5);
// assigns 4.0 to tmpVal

tmpVal = LLpr2.getAt(0.5,1.5);
// calculates interpolation factor for
        // x=0.5, y=1.5
        // interpolates value for (0.5,1.5) as -2.875 and
        // assigns it to tmpVal

tmpVal = LLrp2.getAt(20,10);
// calculates extrapolation factor for x=20, y=10
// extrapolates value for (20,10) as 5.0 and
// assigns it to tmpVal

With characteristic maps, too, separating the search and interpolate steps in tables can be more efficient. In that case, linear interpolation is performed as follows:

LLpr2.search(1,3);
// sets x sample point to 1 and y sample point to 3

tmpVal = LLpr2.interpolate();
// assigns 1.0 to tmpVal

LLpr2.search(4,4);
// calculates interpolation factor for x=4, y=4

tmpVal = LLrp2.interpolate()
// interpolates value for (4,4) as 3.143 and
// assigns it to tmpVal

In addition to the interpolation routines provided by ASCET, you can add user-defined interpolation routines, or you can mark interpolation routines as high-resolution.

Note
The interpolation routines provided with ASCET are examples, not intended to be used in production or in ECUs running in a vehicle. See section "Interpolation Routines" in the ASCET‑SE user guide.