MATLAB executing else block in event locator function even though if condition is true

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shaunaksinha 2017-1-18

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https://ww2.mathworks.cn/matlabcentral/answers/320952-matlab-executing-else-block-in-event-locator-function-even-though-if-condition-is-true

评论： Image Analyst 2017-1-18

I am trying to simulate a two-tank liquid level problem. One of the 'states' (control engg. terminology) is defined by a differential equation that I am integrating using ode45. The integration stops when the associated event function gets value=1 based on a condition [which is that the difference between the liquid levels in both tanks is less than a certain value(0.001)]. While debugging I see that the if condition evaluates true after certain number of iterations but MATLAB still executes the else block thus making the integration endless.

UPDATE:It looks like it is executing the if block now but the integration is not terminating even though value=1 is executed. Here is the code:

%ODE function

function hdot = q4_ode_func(t, h)
constants;
hdot=zeros(2,1)
h1=h(1); h2=h(2);
diff1=h1-h0;
diff2=h1-h2;
if(diff1>0)
    Qv1=1;
else
    Qv1=-1;
end
if(diff2>0)
    Qv2=1;
else
    Qv2=-1;
end
hdot(1) = (1/A)*(-Qv1-Qv2);
hdot(2) = (1/A)*(Qv1+Qv2);

%Event locator function

function [value,isterminal,direction] = q2
constants;
if h(2)<4.8
value=1;
else
value =0;
end
isterminal = 1;
direction = 0;
end

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Image Analyst 2017-1-18

Just how is function q2 supposed to get array h when h is not passed into it via the argument list, nor is it a global variable, nor do you get it via getappdata()?

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