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Analytic function with multiple lower/upper limits

Posted Aug 25, 2015, 3:16 p.m. EDT Heat Transfer & Phase Change, Materials, Parameters, Variables, & Functions, Structural Mechanics Version 4.4 2 Replies

Yunbo Liu
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Hi,

I'm trying to define an analytic function in the global definition that has multiple definitions over different range. For example, the expression is x, when 0<x<=20; the expression is 2x^2+1 when 20<x<=50, so on. How should I combine them into one analytic function? Or should I just define a bunch of them then somehow use all of them later (in the material properties for example)?

Any help is much appreciated! Thanks!
2 Replies Last Post Aug 26, 2015, 2:21 a.m. EDT
Lasse Murtomäki
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Posted: 9 years ago Aug 26, 2015, 2:18 a.m. EDT
Hi

I suggest using my favorite, flc2hs:

f(x) = x*(1 - flc2hs(x-20,d)) + (2x² + 1)*flc2hs(x-20,d)*(1-flc2hs(x-50,d)) + flc2hs(x-50,d)*(next function)...

where d is the interval within the step is taken; I use d = 0.001.

A picture attached.

BR
Lasse



Hi I suggest using my favorite, flc2hs: f(x) = x*(1 - flc2hs(x-20,d)) + (2x² + 1)*flc2hs(x-20,d)*(1-flc2hs(x-50,d)) + flc2hs(x-50,d)*(next function)... where d is the interval within the step is taken; I use d = 0.001. A picture attached. BR Lasse

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Gunnar Andersson COMSOL Employee

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Posted: 9 years ago Aug 26, 2015, 2:21 a.m. EDT
This is what the Piecewise function type is for.
This is what the Piecewise function type is for.

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