the estimated integral value, abstol is the
%   absolute error tolerance, and reltol is the relative error tolerance.
%   Usually the reltol determines the accuracy of the estimation; however,
%   if | I | is rather small, then abstol determines the accuracy of the
%   estimation.
% 
% It is recommended to use *compInteg* for estimating the integral
% repeatedly after the object initialization.
%
% OutP is the structure holding additional output params, more details
% provided below. Input f is a function h