Solve and plot system in x and y with varying constants e and t

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LUCA D'AMBROSIO
LUCA D'AMBROSIO 2024-7-1
编辑： Torsten 2024-7-2
Ran in:
hello,
i am having troubles solving the following problem:
solve and plot for x and y
x+y+e+t>=0
And
x*y-e*t>=0
where x and y are the two variables while e and t are two constants whose values has to vary in a range
i am trying to see the effect of e and t on the system represented by x and y.
basically i would like to obtain on the same graph different curves in x and y for a fixed number of combinations of e and t.
my code so far is:
n= 21;
x = linspace(-100, 100, n);
y = linspace(-100, 100, n);
[X, Y] = meshgrid(x, y);
a = 50;
b = 5;
e = linspace(-a, a, b);
t = linspace(-a, a, b);
Z = zeros(n, n);
for k = 1:b
for s = 1:b
b = X + Y + e(k) + t(s);
d = X.*Y - e(k).*t(s);
for i= 1:n
for j= 1:n
if b(i,j) >= 0
Z(i,j) = d(i,j);
else
Z(i,j) = -1;
end
end
v = [0, 0];
contour(X, Y, Z, v, 'LineWidth', 1.5)
grid on
hold on
end
end
end
Warning: Colon operands must be real scalars. This warning will become an error in a future release.
Warning: Colon operands must be real scalars. This warning will become an error in a future release.
Warning: Colon operands must be real scalars. This warning will become an error in a future release.
Warning: Colon operands must be real scalars. This warning will become an error in a future release.
could anybody please give me any suggestions on how to improve it, as the result so far is not what i expect.
thank you very much

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采纳的回答

Torsten
Torsten 2024-7-1
移动：Torsten 2024-7-1
basically i would like to obtain on the same graph different curves in x and y for a fixed number of combinations of e and t.
Inequalities produce 2d-regions, not 1d-curves as feasible sets. That's why it is difficult or even impossible to find an understandable plot of more than one feasible region for different values of e and t in one graph.
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更多回答（1 个）

Walter Roberson
Walter Roberson 2024-7-1
移动：Walter Roberson 2024-7-1
for k = 1:b
for s = 1:b
b = X + Y + e(k) + t(s);
You redefine b, which was used as the limit of your for loops.

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