For prefilter methods, returns the analytical kernel representing
"disagg then aggregate" as a small convolution on the coarse grid.
Useful for diagnostics and for understanding the bias structure of
standard interpolation.
Usage
roundtrip_kernel(method, fact)
Arguments
- method
Character. Currently `"bilinear"` (3x3 kernel) and
`"cubic"` (5x5 kernel, Keys convention with a = -0.5) are supported
as prefilter methods. (Pycnophylactic disaggregation is iterative
and does not have a round-trip kernel in this sense.)
- fact
Integer disagg factor.
Value
A square odd-sized numeric matrix.