shortcol <- function(xx, b=5, h=15)
{
  ##########################################################################
  #
  # SHORT COLUMN FUNCTION
  #
  # Authors: Sonja Surjanovic, Simon Fraser University
  #          Derek Bingham, Simon Fraser University
  # Questions/Comments: Please email Derek Bingham at dbingham@stat.sfu.ca.
  #
  # Copyright 2013. Derek Bingham, Simon Fraser University.
  #
  # THERE IS NO WARRANTY, EXPRESS OR IMPLIED. WE DO NOT ASSUME ANY LIABILITY
  # FOR THE USE OF THIS SOFTWARE.  If software is modified to produce
  # derivative works, such modified software should be clearly marked.
  # Additionally, this program is free software; you can redistribute it 
  # and/or modify it under the terms of the GNU General Public License as 
  # published by the Free Software Foundation; version 2.0 of the License. 
  # Accordingly, this program is distributed in the hope that it will be 
  # useful, but WITHOUT ANY WARRANTY; without even the implied warranty 
  # of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 
  # General Public License for more details.
  #
  # For function details and reference information, see:
  # http://www.sfu.ca/~ssurjano/
  #
  ##########################################################################
  #
  # INPUTS:
  #
  # xx = c(Y, M, P)
  # b  = width of cross-section (optional), with nominal value 5
  # h  = depth of cross-section (optional), with nominal value 15
  #
  ##########################################################################
  
  Y <- xx[1]
  M <- xx[2]
  P <- xx[3]
  
  term1 <- -4*M / (b*(h^2)*Y)
  term2 <- -(P^2) / ((b^2)*(h^2)*(Y^2))
  
  y <- 1 + term1 + term2
  return(y)
}