PWLINT: Piecewise Linear Integration

Return positive and negative areas, assuming a piecewise linear function

Description

PWLINT.m
 Calculate the positive and negative area under a curve
 using trapezoids, assuming a piecewise linear function

Requires insertrows:
  http://www.mathworks.com/matlabcentral/fileexchange/9984

Inspired by this thread:
  http://www.mathworks.com/matlabcentral/newsreader/view_thread/252131

Usage:
  [Apos, Aneg, Anet] = pwlint(x,y)
       x: vector of independent variable
       y: vector of dependent variable
    Apos: area between y=0 and positive y values
    Aneg: area between y=0 and negative y values
    Anet: Apos+Aneg; equal to trapz(x,y)

See also TRAPZ, SUM

Acknowledgements

The author wishes to acknowledge the following in the creation of this submission:
INSERTROWS (v2.0, may 2008)

• Required Products: MATLAB
• MATLAB release: MATLAB 7.12 (2011a)