integral from 0  to 1  f(x)= function (x) {
    n++;
    return Math.log(x);
}
estimated integral =	 -0.9999999999979974 
exact integral      =	 -1 
estimated error     =	 3.50824136754738e-10 
actuall error       =	 2.0026202918188574e-12 
npoints= 9764

integral from 0  to 1  f(x)=: function (x) {
    n++;
    return Math.log(x) / Math.sqrt(x);
}
estimated integral =	 -3.9999999999999587 
exact integral      =	 -4 
estimated error     =	 3.948691811854536e-10 
actuall error       =	 4.1300296516055823e-14 
npoints= 64176

integral from 0  to 1  f(x)=sqrt(1-(x-1)^2); acc=eps= 1e-14
estimated integral *4 =	 3.141592653589793 
pi                    =	 3.141592653589793 
estimated error       =	 7.362213709219048e-14 
actuall error         =	 0 
npoints= 123928