How do I plot and return the values of multiple intersections between a function and zero?
显示 更早的评论
Hello,
I need to find the intersection between the det_a function and zero, return the values, and plot the intersections. Here's what I did so far
x = linspace(0,18,1000);
det_a = sin(x).*cosh(x) - cos(x).*sinh(x);
zr = zeros(size(x));
figure
plot(x,det_a,x,zr,'--')
grid on
ylim([-10 10])
xlabel('\betal')
The plot can be seen here:
I haven't found any easy method of doing this, I've tried using the find and intersect functions but they only return one value. Any help would be appreciated, thanks in advance!
采纳的回答
Here's one possibility (though you get repeated results for the roots!):
det_a = @(x) sin(x).*cosh(x) - cos(x).*sinh(x);
x=0:18;
zr = zeros(1,numel(x));
for i = 1:numel(x)
zr(i) = fzero(det_a, x(i));
end
disp(zr)
figure
xx = linspace(0,18,100);
plot(xx,det_a(xx),zr,0,'o')
grid on
ylim([-10 10])
xlabel('\betal')
6 个评论
Gerry Oscar
2021-10-20
Gerry Oscar
2021-10-20
Alan Stevens
2021-10-20
Simply add 2 to the end of the det_a function definition.
Gerry Oscar
2021-10-20
fzero finds the value of x that makes the function det_a equal zero. So if it makes det_a+2 equal zero, then det_a must be -2.
Something like this:
det_a = @(x) sin(x).*cosh(x) - cos(x).*sinh(x);
det_b = @(x) det_a(x) + 2;
x=0:18;
zr = zeros(1,numel(x));
for i = 1:numel(x)
zr(i) = fzero(det_b, x(i));
end
disp(zr)
figure
xx = linspace(0,18,100);
plot(xx,det_a(xx),zr,-2,'o')
grid on
ylim([-10 10])
xlabel('\betal')
Gerry Oscar
2021-10-21
更多回答（1 个）
KSSV
2021-10-20
0 个投票
You can consider using this: https://in.mathworks.com/matlabcentral/fileexchange/22441-curve-intersections
类别
在 帮助中心 和 File Exchange 中查找有关 z-transforms 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
