Pullback computation is hanging. [closed]

asked 2018-01-29 17:28:30 +0200

Jeremy Lane gravatar image

updated 2019-08-29 18:35:37 +0200

FrédéricC gravatar image

I have the following code:

M = Manifold(3, 'M')
X.<x,y,z> = M.chart()

N = Manifold(3, 'N')
XN.<a,b1,b2> = N.chart()

omega = N.diff_form(2)
omega[0,1] = 2*b2/a^3
omega[0,2] = -2*b1/a^3
omega[1,2] = -2/a^2

Then I define a map M to N.

r = sqrt(x^2+y^2+z^2)
t = var('t', domain='real')
STSa = r^(1/2)*(r*cosh(2*r*t) - z*sinh(2*r*t))^(-1/2)
STSb1 = (x*sinh(2*r*t)/r)*STSa
STSb2 = (y*sinh(2*r*t)/r)*STSa

STS = M.diffeomorphism(N, [STSa, STSb1, STSb2])

Finally, I attempt to compute the pullback of omega to M by the map STS:

s = STS.pullback(omega)

Unfortunately, the program runs and runs and nothing ever comes out. Can anyone identify the issue? Of course, the Jacobian of the map STS will not be very nice, but this pullback should be perfectly computable.

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Closed for the following reason duplicate question by tmonteil
close date 2018-01-29 19:55:40.215453