Dear Malik

I hope the attached m-file can help you. A sinusoidal curve is intersected with a horizontal line. you should find the crossing point of these two curves. Due to the digitized points of curves and sampling frequency, you can not find the exact point.

Regards

If the file you have is an image(.png,.jpg,.bmp etc), maybe you should use an image recognition way:

1.convert it to an image black and white;

2.find all your points.

3.find your intersections. You can click on the images if you are able to open it by matlab, or alternatively, you can use some codes to extract them depends on what are your points like.

As Mohammad said, there is always a difference between what you find and the exact value.

Hi,

you could check the 'Curve Intersections' contribution on Matlab File Exchange, it seems to correspond to what you need.

http://www.mathworks.com/matlabcentral/fileexchange/22441-curve-intersections

regards,

http://www.mathworks.com/matlabcentral/fileexchange/22441-curve-intersections

you can easily check the curve values in an interval which you know the intersecting points belong to.

for example let the interval is [a, b] and the horizontal line is y=K and the curve is C.

A simple code:

for p=a: 0.01: b - .0.01

     if  (C(p)-K)*(C(p+ 0.01)-K) < 0

      then p is the intersecting point

    end of if

end of for

B. RADI, A. EL HAMI, Mathématique numérique pour l’ingénieur, Utilisation de MATLAB: Cours, exercices et problèmes de synthèse corrigés. Editions-Ellipses, Numéro ISBN 978-2-7298-5279-5, Novembre 2010 (240 pages, niveau second cycle)

Can someone explain how to find  points of intersection of several curves plotted on xy plane which are allowed to intersect only once. See the attached.

hi mallik i have this problem if you solve it please send me your soloution

hi dear

please send me email and i send you this code.

my email address is [email protected]

i hope have good time.

thank you.

bye