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How to calculate intersection between the domains of two functions?

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Mr. 206 2018-10-8

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评论： Mr. 206 2018-10-9

采纳的回答： KSSV

I have two column vectors (f and g). From this two vector how can i calculate the Delta (in picture).

The picture is just an example, I need an universal way to calculate the Delta.

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Torsten 2018-10-8

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Two column vectors f and g are not enough to draw the above curves.

Mr. 206 2018-10-8

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编辑：Mr. 206 2018-10-8

f and g are two output vectors from x_f,y_f and x_g,y_g

Torsten 2018-10-8

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在 MATLAB Online 中打开

ok, then

delta = min(max(x_f,x_g)) - max(min(x_f,x_g))

Mr. 206 2018-10-8

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error: max: nonconformant arguments (op1 is 9x1, op2 is 11x1) error: evaluating argument list element number 1

Here x_f and x_g is not meant to be equal length

Torsten 2018-10-8

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在 MATLAB Online 中打开

Sorry, should be

delta = min(max(x_f),max(x_g)) - max(min(x_f),min(x_g))

Mr. 206 2018-10-8

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Is this code only based on the picture? Or what ever the position of f and g, it will gonna work?

Mr. 206 2018-10-8

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And is there a way to find out the common area between two graphs?

Torsten 2018-10-8

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编辑：Torsten 2018-10-8

在 MATLAB Online 中打开

If x_f and x_g are connected, this should work for the general case:

delta = max(min(max(x_f),max(x_g)) - max(min(x_f),min(x_g)),0)

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KSSV 2018-10-8

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编辑：KSSV 2018-10-8

在 MATLAB Online 中打开

delta = max(g)-min(f)

I mean, the value of g at y maximum - the value of f at y minimum.

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Mr. 206 2018-10-8

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编辑：Mr. 206 2018-10-8

Thanks for your reply. But as i said, the picture is just for understanding. I need an universal way to calculate the common domain. Because from the vectors it is not evident like the graph.

KSSV 2018-10-8

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The above is the universal way....if not share your data....let me check.

Mr. 206 2018-10-8

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编辑：Mr. 206 2018-10-8

在 MATLAB Online 中打开

For example if 'f' is generated by

x_f  =  [1.36; 1.26; 1.15; 1.07; 1.04; 0.975; 0.919; 0.902; 0.85]
y_f  =  [8.166216269;7.843848638;7.365180126;7.170119543;7.192934221;6.956545443;6.459904454;6.257667588;5.379897354]

and 'g' is generated by

x_g  = [1.43;1.33;1.25;1.18;1.11;1.05;1;0.952;0.909;0.87;0.833]
y_g  = [9.193091461;8.14221752;7.560356469;7.320262202;7.209229304;7.139303413;7.064348687;6.618999297;6.065270152;5.49321781;4.925745302]

KSSV 2018-10-8

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编辑：KSSV 2018-10-9

在 MATLAB Online 中打开

f = [x_f y_f] ;
g = [x_g y_g] ;
plot(f(:,1),f(:,2))
hold on
plot(g(:,1),g(:,2))
% Get delta 
[val1,idx1] = min(f(:,1)) ; f_min = f(idx1,2) ;
[val2,idx2] = max(g(:,1)) ; g_max = g(idx2,2) ;
d = g_max-f_min
P = InterX(f,g) ;