unmkpp

Extract piecewise polynomial details

Syntax

[breaks,coefs,L,order,dim] = unmkpp(pp)

Description

[breaks,coefs,L,order,dim] = unmkpp(pp) extracts information from the fields of the piecewise polynomial structure pp.

Examples

Unwrap Piecewise Polynomial Information

Create a piecewise polynomial structure for the polynomial $$f(x)=x^2+x+1$$ on the interval [0 3], and then extract the information from the fields of the structure.

pp = mkpp([0 3],[1 1 1])

pp = struct with fields:
      form: 'pp'
    breaks: [0 3]
     coefs: [1 1 1]
    pieces: 1
     order: 3
       dim: 1

[breaks,coefs,L,order,dim] = unmkpp(pp)

breaks = 1×2

     0     3

coefs = 1×3

     1     1     1

L = 1

order = 3

dim = 1

Input Arguments

pp — Piecewise polynomial

structure

Piecewise polynomial, specified as a structure. You can create pp using spline, pchip, interp1, or the spline utility function mkpp.

Output Arguments

breaks — Break points

vector

Break points, returned as a vector of length L+1 with strictly increasing elements that represent the start and end of each of L intervals.

coefs — Polynomial coefficients

matrix

Polynomial coefficients, returned as an L-by-k matrix with each row coefs(i,:) containing the local coefficients of an order k polynomial on the ith interval, [breaks(i),breaks(i+1)].

L — Number of intervals

scalar

Number of intervals, returned as a scalar.

order — Order of polynomials

scalar

Order of polynomials, returned as a scalar.

dim — Dimension of target

scalar | vector

Dimension of target, returned as a scalar or vector.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• pp must be a valid piecewise polynomial structure created by mkpp, spline, or pchip in MATLAB^® or by the code generator.

• Code generation does not support pp structures created by interp1 in MATLAB.

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

Version History

Introduced before R2006a