# Understanding Units of dex^-1 in Number Density Measurements

• v0lD
In summary, the conversation is about the units used in a number density expressed in Mpc^-3 dex^-1, specifically the meaning of dex^-1. Dex is a logarithmic unit used in astronomy, and dex^-1 is equivalent to 10^-1, or 0.1. While the purpose of using dex^-1 in this context may seem unclear, it is a common unit used in plots in astronomy papers.
v0lD
Hi,

I've come across a number density expressed in units of Mpc^-3 dex^-1; I understand the Mpc^-3 but not the dex^-1. I know dex is some kind of log scale with n dex = 10^n but I'm not sure what dex^-1 means and was wondering if anyone could help.

Thanks!

I got this from google (dex unit)

dex
a logarithmic unit being used in astronomy. Originally, dex was a convenient function defined by dex (x) = 10x. But the notation is now being used after the exponent in expressions such as -.043 dex, meaning 10-.043. Thus 1 dex equals a factor of 10, making the dex identical to the bel. The name "dex" is a contraction of "decimal exponent."

Thanks - I'd found that same definition. But I'm still not 100% sure what the dex^-1 means. I mean, if 1 dex is 10 then maybe 1 dex^-1 is 0.1? But if it's just a constant factor of 0.1 to be applied to each data point then it seems pointless

I've seen Mpc^-3 dex^-1 used in plots in papers so I was hoping it was a common definition that someone would be familiar with.

## 1. What does "dex^-1" mean?

"dex^-1" is a scientific notation that represents a unit of measurement. In this case, it stands for "per decibel". This means that the value being measured is being divided by decibels.

## 2. How do I convert units of dex^-1 to other units?

To convert units of dex^-1 to other units, you will need to know the specific conversion factor for the unit you are trying to convert to. This may vary depending on what you are measuring and what units you are converting to.

## 3. What are some common uses for units of dex^-1?

Units of dex^-1 are commonly used in fields such as acoustics, electronics, and telecommunications. It is often used to measure the level of sound, signal strength, and attenuation.

## 4. How do I perform calculations involving units of dex^-1?

To perform calculations involving units of dex^-1, you will need to make sure that all values being used have the same units. If not, you will need to convert them to the same units before performing the calculation. You can then use basic mathematical operations such as addition, subtraction, multiplication, and division.

## 5. Are units of dex^-1 the same as decibels?

No, units of dex^-1 and decibels are not the same. Decibels are a unit of measurement for the ratio of two values, while units of dex^-1 are a unit of measurement per decibel. However, they are often used together in measurements and calculations.

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