mkpp

Syntax

pp = mkpp(breaks, coefs)

pp = mkpp(breaks, coefs, d)

Inputs

breaks

The coordinates that define the intervals for each polynomial piece.

The values are assumed to be in strictly increasing order.

Dimension: vector

coefs

The coefficients of each polynomial piece.

In the case of a 2D matrix, the first dimension is the number of polynomial pieces and the second dimension is the number of polynomial coefficients.

In the case of an ND matrix, the matrix is viewed as an array of piecewise polynomials. The leading dimensions of coefs are the dimensions of the pp array. The last two dimension lengths are the number of polynomial pieces, and the number of polynomial coefficients for each piece.

Dimension: matrix

d

The dimensions of the array of piecewise polynomials in coefs.

When coefs is a 2D matrix, d is 1.

Type: integer

Dimension: scalar | vector

Outputs

pp

The piecewise polynomial struct.

The members are as follows:

breaks

The input intervals vector.

coefs

The input coefficients. In the ND case the matrix is reshaped into 2D upon return.

dim

The dimensions vector.

form

The form, 'pp'.

order

The degree of the polynomial plus 1, which is the number of coefficients. This is the spline order, rather than polynomial order.

pieces

The number of piecewise polynomial segments, which is length(breaks) - 1.

Example

breaks = [10, 20, 30, 40, 50];
L = length(breaks) - 1;
order = 3;
coefs = zeros(L, order);
coefs(1, :) = [2, 3, 4];
coefs(2, :) = [3, 4, 5];
coefs(3, :) = [4, 5, 6];
coefs(4, :) = [6, 7, 8];
pp = mkpp(breaks,coefs)

R = poly([1,3,5])

pp = struct [
  breaks: [Matrix] 1 x 5
  10  20  30  40  50
  coefs: [Matrix] 4 x 3
  2  3  4
  3  4  5
  4  5  6
  6  7  8
  dim: 1
  form: pp
  order: 3
  pieces: 4
]