# Thread: partial derivatives of functions wrt to another function?

1. ## partial derivatives of functions wrt to another function?

I came across this problem in a text I am using currently and was confused by the notation and am not sure of the answer

given a function $\displaystyle f = h(g_1, g_2, g_3)$
if $\displaystyle h=x^2 - yz$ and $\displaystyle f = h(x+y, y^2,x+z)$ then is it correct to apply the pointwise vector coordinate function and get $\displaystyle f = (x+y)^2 -y^2(x+z)$

This seemed like a trivial problem but the notation really confuses me.

2. ## Re: partial derivatives of functions wrt to another function?

Originally Posted by knkumar
I came across this problem in a text I am using currently and was confused by the notation and am not sure of the answer

given a function $\displaystyle f = h(g_1, g_2, g_3)$
if $\displaystyle h=x^2 - yz$ and $\displaystyle f = h(x+y, y^2,x+z)$ then is it correct to apply the pointwise vector coordinate function and get $\displaystyle f = (x+y)^2 -y^2(x+z)$

This seemed like a trivial problem but the notation really confuses me.
Yes, that exactly what the notation means: $\displaystyle f= h(x+ y, y^2, x+ z)= (x+y)^2- (y^2)(x+ z)$. The fact that x, y, z are used as "place holders" in both functions is irrelevant.
This is exactly the same as if it were $\displaystyle h(u, v, w)= u^2- vw$