#### Mathmasteriw

##### Junior Member

- Joined
- Oct 22, 2020

- Messages
- 83

- Thread starter Mathmasteriw
- Start date

- Joined
- Oct 22, 2020

- Messages
- 83

- Joined
- Apr 22, 2015

- Messages
- 2,924

Hi Mathmasteriw. That's an interesting form of function notation that I've never seen before. I'm curious. Where did you see it?\(\displaystyle \frac{dv}{dt}(5)\) …

- Joined
- Jan 27, 2012

- Messages
- 7,040

\(\displaystyle \frac{dv}{dt}(5)= \frac{dv(5)}{dt}\).

meaning the derivative of v with respect to t, evaluated at t=5

Some people would prefer the first to the second on the grounds that the second could be interpreted as the derivative of the constant v(5) which is, of course, 0.

- Joined
- Apr 22, 2015

- Messages
- 2,924

Good point, Jomo, but we don't know for sure what the given instructions may have said.… -0.164 is an approximation and not the exact answer.

- Joined
- Apr 22, 2015

- Messages
- 2,924

Thanks, Halls. It prompted me to think of and ponder this:I have seen that [derivative notation] in many places …

\[\frac{\text{dv}}{\text{dt}} \bigg\rvert_{5} = -0.164\]

I've never seen that done, either, but it makes sense.

Agree!… Some people would prefer [\( \; \frac{dv}{dt}(5) \; \)] to [\( \; \frac{dv(5)}{dt} \; \)] …

- Joined
- Dec 30, 2014

- Messages
- 9,678

I have used this notation frequently. I have also seen \(\displaystyle \dfrac{dv}{dt}(5)\) written as \(\displaystyle \dfrac{dv}{dt}|_{t=5}\)

- Joined
- Oct 22, 2020

- Messages
- 83

I owe a lot to what I have learned to this pageHi Mathmasteriw. That's an interesting form of function notation that I've never seen before. I'm curious. Where did you see it?

- Joined
- Aug 27, 2012

- Messages
- 1,015

If memory serves me I've seen this in many forms in Math texts but the above quote is the only way I've seen Physicists write it.\(\displaystyle \dfrac{dv}{dt}|_{t=5}\)

-Dan