Numerical evaluation of an integral, higher order method.

  Q = QUAD8('f',a,b) approximates the integral of f(x) from a

  to b to within a relative error of 1e-3.  'f' is a string

  containing the name of the function.  The function must return

  a vector of output values if given a vector of input values.

  Q = QUAD8(F,a,b,tol) integrates to a relative error of tol.

  Q = Inf is returned if an excessive recursion level is reached,

  indicating a possibly singular integral.

  Q = QUAD8(F,a,b,tol,trace) integrates to a relative error of tol and

  traces the function evaluations with a point plot of the integrand.



  QUAD8 uses an adaptive recursive Newton Cotes 8 panel rule.  See

  also QUAD1D3MCU2.