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Legendre Transformation


Given a function of two variables

df=(partialf)/(partialx)dx+(partialf)/(partialy)dy
(1)
=udx+vdy,
(2)

change the differentials from dx and dy to du and dy with the transformation

 g=f-ux
(3)
dg=df-udx-xdu
(4)
=udx+vdy-udx-xdu
(5)
=vdy-xdu.
(6)

Then

x=-(partialg)/(partialu)
(7)
v=(partialg)/(partialy).
(8)

See also

Legendre Transform

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Cite this as:

Weisstein, Eric W. "Legendre Transformation." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LegendreTransformation.html

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