```Maybe at compile time -O3 is reducing using higher precision mpfr so the closest absolute is 0.
A guess. Jerry``` On Fri, Sep 11, 2026, 11:37 PM Paul Richard Thomas < [email protected]> wrote: > Hi Steve, > > With Fedora 44/x86_64, I see: > 8. 0. 0. 0. 0. 0. 0. 0. 0. 0. > and > 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. with -O3. > > Regards > > Paul > > > > On Sat, 12 Sept 2026 at 05:56, Steve Kargl <[email protected]> wrote: > > > > All, > > > > I can test FreeBSD, but have no easy access to other > > operating systems. Can others compile the following > > program, run the executable, and either post your > > results here or send them to directly. > > > > Thanks. > > > > program besseltest > > > > implicit none > > > > integer i > > integer n(10) > > real(4) x(10), f(10) > > real(4), parameter :: e(10) = [ & > > & 5.64343985e-8, 2.44766589e-8, 1.03553056e-7, -3.53017149e-9, & > > & -6.48150511e-9, 5.15323162e-9, -1.50233475e-7, 1.25245705e-7, & > > & 5.43311032e-8, 1.22055454e-7] > > > > x = [ 2.40482556, 5.52007811, 8.65372791, 11.7915344, 14.9309177, & > > & 18.0710640, 21.2116366, 24.3524715, 27.4934791, 30.6346065] > > > > f = bessel_j0(x) > > > > n = exponent(e); > > f = abs(e - f); > > f = scale(f, 24 - n); > > print '(*(F0.0,1x))', f; > > > > end program besseltest > > > > -- > > steve > > >
