A stencil kernel computes the value of one data or a sub­part of it (the kernel computation domain ) using a numerical expression which takes as input one or more data.
for ex­ample, the stencil kernel illustrated in Figure 1b computes A using B, while the one in Figure 1c computes A using C. a stencil kernel is defined by its numerical expres­sion, a set of input data (only one in the examples), and its unique output data, the result.