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So I'm trying to calculate the frenet thrihedrom in the "clasic" way, (doing an arc length and his integrals) but sage don't let me do a diff of a integral. Here ismy code:

var('t, n')
assume(n > 0)
c=vector((t,t**2,t**3))

l=sqrt(1+4*t*t+9*t**4)
L= l.integral(t, 0, n)

C=vector((t/L,(t/L)**2,(t/L)**3))
T=C.diff(t)

I get this error:

AttributeError: 'sage.rings.rational.Rational' object has no attribute 'diff'

Any idea of how to do a Diff of a integral?

So I'm trying to calculate the frenet thrihedrom in the "clasic" way, (doing an arc length and his integrals) but sage don't let me do a diff of a integral. Here ismy code:

var('t, n')
assume(n > 0)
c=vector((t,t**2,t**3))

l=sqrt(1+4*t*t+9*t**4)
L= l.integral(t, 0, n)

C=vector((t/L,(t/L)**2,(t/L)**3))
T=C.diff(t)

I get this error:

AttributeError: 'sage.rings.rational.Rational' object has no attribute 'diff'

Any idea of how to do a Diff of a integral?