envelope.logquad: Build a piecewise-quadratic envelope given log of a function
In jmhewitt/dsdive: Discrete Space Models for Dive Trajectories of Animals

Build a piecewise-quadratic envelope given log of a function

envelope.logquad(
  breaks,
  logf,
  d.logf,
  dd.logf.sup,
  anchors = breaks[1:(length(breaks) - 1)]
)

`breaks`	Breakpoints that define the start and end points of each interval over which a piecewise-quadratic function will be defined.
`logf`	Value of log(f) at the anchors.
`d.logf`	Derivative of log(f) evaluated at the anchors.
`dd.logf.sup`	Supremum of second derivative of log(f) over each interval
`anchors`	Locations within the intervals (defined by `breaks`) at which the polynomial approximation will be centered