Construct a piecewise polynomial (pp) structure from sample points breaks and coefficients coefs.
breaks must be a vector of strictly increasing values. The number of
intervals is given by ni = length (breaks) - 1
.
When m is the polynomial order coefs must be of size: ni x m + 1.
The i-th row of coefs, coefs (i,:)
, contains the
coefficients for the polynomial over the i-th interval, ordered from
highest (m) to lowest (0).
coefs may also be a multi-dimensional array, specifying a vector-valued
or array-valued polynomial. In that case the polynomial order is defined
by the length of the last dimension of coefs. The size of first
dimension(s) are given by the scalar or vector d. If d is not
given it is set to 1
. In any case coefs is reshaped to a 2-D
matrix of size [ni*prod(d m)]
See also: unmkpp, ppval, spline, pchip, ppder, ppint, ppjumps.
The following code
# linear interpolation x = linspace (0,pi,5)'; t = [sin(x), cos(x)]; m = diff (t) ./ (x(2)-x(1)); b = t(1:4,:); pp = mkpp (x, [m(:),b(:)]); xi = linspace (0,pi,50); plot (x,t,"x", xi,ppval (pp,xi)); legend ("control", "interp");
Produces the following figure
Figure 1 |
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Package: octave