On Thursday, November 5, 2015 at 3:56:09 PM UTC+2, Imran Ali wrote:
>
> If I simply hard code each metric, every thing works properly. For
> example, take egg carton surface,
>
> from sympy.diffgeom import Manifold, Patch, CoordSystem, TensorProduct
> from sympy import sin,cos
> dim = 2
> m = Manifold("M",dim)
> patch = Patch("P",m)
> system = CoordSystem('egg_carton', patch, ["u", "v"])
> u,v = system.coord_functions()
> du,dv = system.base_oneforms()
> metric = (sin(v)**2*sin(u)**2 + 1)*TensorProduct(dv, dv) +\
> (cos(v)**2*cos(u)**2 + 1)*TensorProduct(du, du) +\
> (-cos(2*v - 2*u)/8 + cos(2*v + 2*u)/8)*TensorProduct(du, dv)
> +\
> (-cos(2*v - 2*u)/8 + cos(2*v + 2*u)/8)*TensorProduct(dv, du)
> I can use any of the metric_to_* functions without getting the ValueError.
>
> By the way, that metric expression, is from my code. My code produces the
> correct metric two form expression. But when I use it as argument for any
> of the metric_to_* functions, I get the ValueError. What gives ?
>
> I posted the question on SO :
>
>
> http://stackoverflow.com/questions/33545982/valueerror-using-sympy-diffgeom-when-using-metric-to-functions
>
>
It is not clear how u, v, du, dv are constructed in your SO question. If
you could post srepr(u) and srepr(du), it might be possible to say more.
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