what does it mean when a partial derivative has a prime on it? usually i just see partial derivatives as f and a subscript x but i recently came across f with a subscript x and a prime on the top. just curious, what does that mean?

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- Oct 27th 2009, 05:28 PMoblixpsquestion on notation for partial derivatives
what does it mean when a partial derivative has a prime on it? usually i just see partial derivatives as f and a subscript x but i recently came across f with a subscript x and a prime on the top. just curious, what does that mean?

- Oct 27th 2009, 05:45 PMadkinsjr
- Oct 27th 2009, 10:37 PMoblixps
- Oct 28th 2009, 09:22 AMHallsofIvy
One possibility: f is a function of position and

**time**(so it is a physics problem) and they are using the ' to distinguish differentiation with respect to time, t, while using the partial derivative to indicate differentiation with respect to a space variable.

Another possibility: there are (at least) two different "f" functions, one called f and the other called f' and the prime is used only to distinguish functions.

Which, if either, of those is correct would depend on the context.