Find intersections of curves

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SAM
SAM on 24 Apr 2022
Edited: Torsten on 24 Apr 2022
hello, I have the following two formulas and I want to know How can I find the intersection point of the two curves and how to mark it on the graph?
syms bL
ab=8.0901*10^(-5);
f12=ab*sinh(2*bL);
f22=sin(2*(ab)*bL);
fplot(bL,f12,'-or');
hold on
fplot(bL,f22,'-ob');
thank you

Accepted Answer

Matt J
Matt J on 24 Apr 2022
Edited: Matt J on 24 Apr 2022
syms bL
ab=8.0901*10^(-5);
f12=ab*sinh(bL);
f22=sin(2*(ab)*bL);
bLmax=fzero(matlabFunction(f12-f22) ,2 );
rts=[-bLmax,0,+bLmax];
fnum=matlabFunction(f12);
fplot(bL,f12,'-r');
hold on
fplot(bL,f22,'-b');
plot(rts,fnum(rts),'ok','MarkerFaceColor','k')
hold off
xlim([-3,3])
ylim([-0.001,0.001])

More Answers (2)

Torsten
Torsten on 24 Apr 2022
bL = 0 is the intersection point.
hold on
plot(0,0,'.')
  2 Comments
SAM
SAM on 24 Apr 2022
I want a value other than 0
Torsten
Torsten on 24 Apr 2022
Edited: Torsten on 24 Apr 2022
a = 8.0901e-5;
fun1 = @(a,x) a*sinh(x);
fun2 = @(a,x) sin(2*a*x);
f=@(a,x)fun1(a,x)-fun2(a,x)
x1 = fzero(@(x)f(a,x),[2,2.5])
x2 = fzero(@(x)f(a,x),[-3,-2])
x=-2.5:0.01:2.5;
plot(x,fun1(a,x))
hold on
plot(x,fun2(a,x))
hold on
plot(x1,fun1(a,x1),'.')
hold on
plot(x2,fun1(a,x2),'.')
hold on
plot(0,0,'.')

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Sam Chak
Sam Chak on 24 Apr 2022
Edited: Sam Chak on 24 Apr 2022
Try performing analysis on the problem first, before quickly attempting to solve it. The hyperbolic sine is unbounded. Do you think there are intersections other than the trivial solution at bL = 0? Seems there are another two at .

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