# Computing uncertainties

#### fayan77

Hello, took a year off school and starting school soon. So I'm shaking off the rust and remembered in my previous lab courses we were supposed to compute uncertainties but I never really understood how that works. All I remember was its something to do with pythagorean theorem. I want to really understand this mathematical concept for I will be taking many more labs at university level and want to be prepared.

Related General Engineering News on Phys.org

Homework Helper
Gold Member
2018 Award
What you are referring to I believe is e.g. if $V=V(X,Y)$ where $X$ has uncertainty $\Delta X$, and $Y$ has uncertainty $\Delta Y$, then the uncertainty $\Delta V$ satisfies $(\Delta V)^2=(\frac{\partial{V}}{\partial{X}})^2 (\Delta X)^2+(\frac{\partial{V}}{\partial{Y}})^2 (\Delta Y)^2$. Perhaps someone can find a link to something that spells this idea out in more detail. $\\$ A simple example of the above is the case where $V=X+Y$. Then $(\Delta V)^2=(\Delta X )^2+(\Delta Y )^2$. $\\$ Meanwhile, the above can be generalized to more variables, e.g. $V=V(X,Y,Z,...)$.

Last edited:

"Computing uncertainties"

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving