Hi, can anyone tell why this evaluation is correct:
var('y')
h(x,y) = sqrt(1-(cos(2*y)*sin(2*x)))
G(x,y) = sum([comp^2 for comp in diff(h)])
diff(G)(*vector((0.1,0.75)))
(0.788319732748083, -0.281637345440034)
But this evaluation, using RDF, is not correct:
diff(G)(*vector(RDF,(0.1,0.75)))
ValueError: negative number cannot be raised to a fractional power
I am aware that the error is related with the question https://ask.sagemath.org/question/7820/fractional-power-to-negative-number/, but I would expect the same behavior in both cases, with and without RDF.