Set up an OR argument for equation

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Grant Murdoch
Grant Murdoch 2019-3-18
回答： Jos (10584) 2019-3-18
I am using Matlab to simulate the pounding bwtween structures during earthquake events.
To do this the equation for the pounding force, F, must change depending on the output of another parameter. The conditions are:
F(t) = k*s + c*v(t) when v(t) > 0
F(t) = k*s when v(t) < 0
What is the best way to set this up?
The code for both the equations above is:
fp = (k_inp*(x1-x2-gap)+c_inp*(xdot_1-xdot_2)).*(sign(x1-x2-gap)+1)/2 when v(t) > 0
fp = (k_inp*(x1-x2-gap) when v(t) < 0
where v(t) = (xdot_1-xdot_2)).*(sign(x1-x2-gap)+1)/2
Thanks in advance for any replies.

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采纳的回答

Torsten
Torsten 2019-3-18
编辑：Torsten 2019-3-18
v = (xdot_1-xdot_2)).*(sign(x1-x2-gap)+1)/2;
if v > 0
fp = (k_inp*(x1-x2-gap)+c_inp*(xdot_1-xdot_2)).*(sign(x1-x2-gap)+1)/2
else
fp = k_inp*(x1-x2-gap)
end

更多回答（2 个）

Jos (10584)
Jos (10584) 2019-3-18
Can't you use logical indexing? A simplified example
v = 10:20
q = v > 13 & v < 18
f(q) = 2*v(q)
f(~q) = 30 + v(q)
Jos (10584)
Jos (10584) 2019-3-18
Simpler, without an if-else:
v = (xdot_1-xdot_2)).*(sign(x1-x2-gap)+1)/2;
fp = (k_inp*(x1-x2-gap) + (v>0) * c_inp * (xdot_1-xdot_2)).*(sign(x1-x2-gap)+1)/2
% |||||||

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