How can I find intersections of curves?

    clear all
    clc
    Reactive_QCP1=[6.708;6.396;6.0911;5.791;5.498;5.210;4.926;4.647;4.371];
    Reactive_QCP2= [17.053;13.255;9.590;6.0533;2.632;-0.683;-3.903;-7.034;-10.083];
    ReactiveChange=(-40:10:40)';
    Graph_1=plot(Reactive_QCP1(:,1),ReactiveChange(:,1),'b');
    grid on
    hold on
    Graph_2=plot(Reactive_QCP2(:,1),ReactiveChange(:,1),'r');
    xlabel('Reactive Power Change of WF [p.u]');
    ylabel('QCPs [Mvar]');
    Graph_3=line([-15 20],[0 0],'color','k');
    hleg2=legend('QCP1','QCP2','Location','NorthEastOutside');

    % I want to see the coordinates where Graph_1 and Graph_3 intersect.
    % How can I do that? Thanks a lot

Answer 1

[Star Strider]

Since ‘Graph3’ is the x-axis where y = 0, you can use interp1 to find the intersection of Graph1:

G1G3Intx = interp1(ReactiveChange, Reactive_QCP1(:,1), 0);

This will give you the value of ‘Reactive_QCP1’ where ‘ReactiveChange’ is zero. Is that what you want?