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Uncertainty with a log function

  • Thread starter sprinks13
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Homework Statement


Im trying to find the uncertainty for a log function. I have that

f = 20log(V_in/V_out)

and i want to know (delta)f

Homework Equations



f = 20log(V_in/V_out)

The Attempt at a Solution



I was going to do it the calculus way:

f = 20log(V_in) -20log(V_out)

df = 20*f*[(dV_in/V_in) - (dV_out/V_out)]

but this doesn't seem right to me. I've never seen subtraction in an error calculation before. And im not sure if this is a relative error or a percent error. I want a relative error (with units), the only problem is that my function has no units, soI'm not sure what I should do in that case (if that makes sense).

Is there another simple formula for log function errors?
 

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