# I Why use the Legendre transform over back substitution

1. Aug 23, 2016

### nashed

In thermodynamics we use a variation of the Legandere Legendre transform to move from one description of the system to another ( depending on what is the control variable...), but I don't understand why choose to use the Legandere Legendre transform over writing x in terms of s=dy/dx and back substituting to y=f(x), please refrain from using differential forms if you can, as much as I tried I just don't seem to have the foundations to understand them (being a physics student) and unfortunately I really don't have the time to try and cover everything needed to understand them.

Mod note: Fixed misspelling of Legendre.

Last edited by a moderator: Aug 23, 2016
2. Aug 28, 2016