Interpolation in mathematics, estimation
of a value between two known data points. A simple example is calculating the
mean (see mean, median, and mode) of two population counts made 10 years apart
to estimate the population in the fifth year. Estimating outside the data points
(e.g., predicting the population five years after the second population count)
is called extrapolation. If more than two data points are available, a curve may
fit the data better than a line. The simplest curve that fits is a polynomial
curve. Exactly one polynomial of any given degree — an interpolating polynomial
— passes through any number of data points.
A graph is an image that represents data symbolically. A graph is used to present complex information and numerical data in a simple, compact format. Bar graphs, line graphs, scatter graphs, and pictographs are some types of graphs. Graphs then, are visual representations of worksheet data. Graphs often makes it easier to understand the data in a worksheet because users can easily pick out patterns and trends illustrated in the graph that are otherwise difficult to see.