Recursive function used by QUAD8 .
[Q,cnt] = quad8stp(F,a,b,tol,lev,w,f,Q0) tries to approximate
the integral of f(x) from a to b to within a relative error of tol.
F is a string containing the name of f. The remaining arguments are
generated by quad8 or by the recursion. lev is the recursion level.
w is the weights in the 8 panel Newton Cotes formula.
x0 is a vector of 9 equally spaced abscissa is the interval.
f0 is a vector of the 9 function values at x.
Q0 is an approximate value of the integral.
See also QUAD8HSRNMC and QUAD .