On Thursday, January 17, 2013 10:57:14 AM UTC-5, Jeroen Demeyer wrote:
>
> On 2013-01-17 15:59, kcrisman wrote:
> > These are weird. This code is (documented to be) only accurate up to a
> > point, because of the inherent craziness of computing such things, but
> > it's good for what it does. But these errors are very different. I'm
> > cc:ing the author in case he can think of any build-time issues like env
> > vars or things in PATH that might make a difference.
> It would be interesting to know which Sage components this uses, such
> that I can rebuild selected parts which might be the cause.
>
sage: ps = polygon_spline([(-1, -1), (1, -1), (1, 1), (-1, 1)])
sage: f = lambda t: ps.value(real(t))
sage: fprime = lambda t: ps.derivative(real(t))
sage: get_systems('m = Riemann_Map([f], [fprime], 0.25, ncorners=4)')
['numpy', 'MPFR']
sage: m = Riemann_Map([f], [fprime], 0.25, ncorners=4)
sage: x = 0.75
sage: get_systems('print "error =", m.inverse_riemann_map(m.riemann_map(x))
- x ')
error = (-0.000291742263558+0.00160874617676j)
[]
sage: print "error =", m.inverse_riemann_map(m.riemann_map(x)) - x
error = (-0.000291742263558+0.00160874617676j)
I really think that's it, too; it's heavily numerical code in Cython and
numpy.
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