A data interpolation widget. Currently, the
data must be imported from a file containing two values on each line,
eg:
If the input is less than the minimum key value (0.1 here), then the
operation outputs the corresponding value (0.3). Similarly if the
input is greater than the maximum (0.9), the corresponding value (1)
is output. If it lies in between two keys (eg 0.2), the the output is
linearly interpolated (0.4).
More formally, a data block is an empirical function, based on a table
of pairs of values (
) read in from
a file. The function's output is linearly interpolated from the data,
ie: