strange quad_qags behavior?



>  Isn't that the best way, or maybe if that doesn't work use to_poly_solve.  %solve(1/expr,x) to
> get the points. Another idea is some analysis of the expression. 

%solve misses many (most) important cases; for example %solve knows nothing about bessel functions. Consider:

  (%i24) quad_qags (1/bessel_j(0,x), x, 2, 10, 'epsrel=1d-10);
  (%o24) [19.18306454272454,49.39600889427612,7077,5]

Oops... bessel_j(0,x) has three zeros in [2, 10] ; sometimes a visual analysis wins:

  (%i25) wxplot2d(bessel_j(0,x),[x,2,10]);

--Barton