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how to re-order factors

asked 2015-02-15 23:41:17 +0200

userX gravatar image

updated 2015-02-17 04:22:38 +0200

kcrisman gravatar image

I have

 x,y, dx, dy= var("x, y, dx, dy");
 def iD(f): return diff(f, x)*dx + diff(f,y)*dy;

iD(x^3*y^5) returns

5*dy*x^3*y^4 + 3*dx*x^2*y^5

is there a way to have it return the differentials always at the end as in

5*x^3*y^4*dy + 3*x^2*y^5*dx

thank you

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answered 2015-02-16 19:05:44 +0200

vdelecroix gravatar image


You would better use differential forms directly

 sage: x, y, z = var('x, y, z')
sage: U = CoordinatePatch((x, y, z))
sage: F = DifferentialForms(U)
sage: form0 = DifferentialForm(F, 0, x^3*y^5)
sage: form0
sage: form0.diff()
3*x^2*y^5*dx + 5*x^3*y^4*dy

The exterior product is also implemented

sage: dx = DifferentialForm(F,0,x).diff()
sage: dy = DifferentialForm(F,0,y).diff()
sage: dx*dy
sage: dy*dx

You can access the documentation by typing

sage: DifferentialForm?

and then press enter. Alternatively, you can have a look to differential forms in the reference manual.

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very nice thank you! its perfect!

userX gravatar imageuserX ( 2015-02-16 20:32:06 +0200 )edit

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Asked: 2015-02-15 23:41:17 +0200

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Last updated: Feb 17 '15