How to graph alternative solution of a function

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Adam Thompson 2020-4-17

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https://ww2.mathworks.cn/matlabcentral/answers/518724-how-to-graph-alternative-solution-of-a-function

HI there, pretty simple question and more of a maths one than a technical MATLAB one.

For each value of Launch Angle there are two solutions for the value of A. I'm plotting one at the moment and want to plot the other. e.g. at launch angle of 10deg, A can equal both 0.21 and 2.2ish

How do I change my code to plot the other solution?

A_values = ones(1,45);
B_values = ones(1,45);
LaunchAngle = ones(1, 45);
for qL = 1:45
   LaunchAngle(1,qL) = qL;
   qLrad = deg2rad(qL);
   Rd = 1.7;   % Y asymptote of curve
   XL = 0;  % Release point x
   X0 = 1.7; % Starting point x
   F = @(A,B) [((-Rd + ((2*Rd) /(1 + exp(A*(X0 - B)))))), (((-2*A*Rd*exp(A*(XL-B)))/((exp(A*(XL-B))+1)^2))-tan(qLrad))];
   AB0 = [1; 1]*1j;
   AB = fsolve(@(b)F(b(1),b(2)), AB0);
   A_values(:,qL) = AB(1)*-1;
   B_values(:,qL) = AB(2);
end
plot(LaunchAngle, A_values, LaunchAngle, B_values);
xlabel('Launch angle (deg)');
ylabel('Required trajectory function parameters');
title('Required trajectory function parameters for launch point x = 0');
legend('A', 'B');