Smoothing function starting point relative to the value of another smoothing function

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aalto-comnet
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Posts: 37
Joined: Fri Dec 07, 2018 9:20 am
Vensim version: DSS

Smoothing function starting point relative to the value of another smoothing function

Post by aalto-comnet »

Hello!

The model below has a variable with two step inputs a and b, with b starting later than a, and another variable with their smoothing equivalents.

Based on the fraction b/a of the step inputs when b starts, I am trying to make the starting point of smoothing b to be relative to the value of smoothing a at this point in time.

For example, in the attached figures, since step b is equal to step a, smoothing b should not start from point 0, but it should start from the same value of smoothing a at this point in time, as shown by the arrow.

Similarly, if step b would be half the value of step a, smoothing b should start from smoothing a/2 at this point in time.

Any ideas?

Thank you! :D
Attachments
test.mdl
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test step.png
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test smooth.png
test smooth.png (761.98 KiB) Viewed 571 times
tomfid
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Posts: 3806
Joined: Wed May 24, 2006 4:54 am

Re: Smoothing function starting point relative to the value of another smoothing function

Post by tomfid »

If you use the SMOOTHI variant, you can specify an expression for the initial value.

That said, I'm not sure what you're trying to do here. Do you want the smoothed B to be constant at about -.06 until time 6? Or are you trying to smooth the difference between b and a, or b and smooth(a)?
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