0],
called the first partial derivative of f with respect to r.
Similarly the derivative of the r = r0, φ
= φ0 slice curve f[r0,θ,φ0]
with respect to θ is denoted
by fθ[r0,θ0,φ0],
called the first partial derivative of f with respect to θ
and the derivative of the r = r0, θ = θ0
slice curve f(r0,θ0,φ)
with respect to φ
is denoted by fφ[r0,θ0,φ0],
called the first partial derivative of f with respect to φ.