Figure Properties - SERC

interp1
2-1190
yi = interp1(x,Y,xi,method,extrapval) returns the scalar extrapval for
out of range values. NaN and 0 are often used for extrapval.
pp = interp1(x,Y,method,'pp') uses the specified method to generate the
piecewise polynomial form (ppform) of Y. You can use any of the methods in the
preceding table, except for 'v5cubic'.
The interp1 command interpolates between data points. It finds values at
intermediate points, of a one-dimensional function fx ( ) that underlies the
data. This function is shown below, along with the relationship between vectors
x, Y, xi, and yi.
f(x)
Interpolation is the same operation as table lookup. Described in table lookup
terms, the table is [x,Y] and interp1 looks up the elements of xi in x, and,
based upon their locations, returns values yi interpolated within the elements
of Y.
Note interp1q is quicker than interp1 on non-uniformly spaced data
because it does no input checking. For interp1q to work properly, x must be a
monotonically increasing column vector and Y must be a column vector or
matrix with length(X) rows. Type help interp1q at the command line for
more information.
Examples Example 1. Generate a coarse sine curve and interpolate over a finer abscissa.
x = 0:10;
x
xi
Y yi