Is My Electric Field Curve Exhibiting Exponential Decay?

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Discussion Overview

The discussion revolves around determining when an electric field curve, obtained from COMSOL, begins to exhibit exponential decay. Participants explore methods for analyzing the curve's behavior, particularly focusing on visual representation and statistical measures.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant suggests plotting the curve on semi-log paper, indicating that a straight line on this type of plot would correspond to exponential behavior on a linear plot.
  • Another participant questions how to identify when the plot transitions from linearity, mentioning the use of R² values to estimate the goodness-of-fit for the curve.
  • Participants provide R² values as examples, indicating a range from 1.0 to 0.95, but express uncertainty about how to interpret these values in the context of linearity.
  • One participant asserts that the curve is no longer linear when it visibly starts to curve on the plot, although this response does not address the statistical aspect raised by others.
  • Another participant notes that low R² values are associated with a low goodness-of-fit, implying a potential lack of linearity.

Areas of Agreement / Disagreement

Participants do not reach a consensus on how to determine when the curve stops being linear, with differing opinions on the interpretation of visual and statistical indicators.

Contextual Notes

Limitations include the reliance on visual interpretation of the plot and the ambiguity surrounding the significance of R² values in determining linearity.

nordmoon
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I have a curve I obtained in COMSOL representing a electric field for m structure. I have to figure how to determine when the curve starts to become exponential decaying at certain regions.

Any idea how to determine when the curve starts becoming exponential decaying from a plot?
 
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Plot the curve on semi-log paper. A straight line there will be equivalent to exponential on a linear plot.
 
How do I see when the plot is no longer linear? I am estimating the curves R2-values (coefficient of determination).

I get values like,

1.0
0.9998
0.9953
0.9915
0.95

etc

I just don't know how to determine when it stops being linear. Do you have any suggestions?
 
I don't understand your concern. When you plot it and it starts to curve then it is no longer linear.
 
Low values of R^2 go together with a low (linear) goodness-of-fit .
 

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