# Integral notation

## Main Question or Discussion Point

if you put the differential dx, dy, and dz in the front of the integrand how do you order it so that it matches the order of which variable you want to integrate first?

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HallsofIvy
Homework Helper
That depends on the "convention" you use. Most people write the differentials after the integrand but even if you write them in front the same convention is used: The differential that appears first (yes, I see your point: you want to use the one nearest the integrand, the last one, don't you) that you integrate with respect to:
$$\int \int \int dxdydz f(x,y,z)$$
implies that you integrate with respect to x first.

Another notation which I like very well is to always keep the integral sign and the dx together, sort of an operator notation:

$$\int dz \int dy \int dx \,f(x,y,z)$$

The integrations are done from right to left.

Last edited:
HallsofIvy