Multiple Curve intersection plot

Hello,

I have 3 vectors : Vph, If & Isc

I plot Vph versus If (O.C.C) and Isc versus If (S.C.C)

after plotting the two curves i need to draw a horizontal line from a value of Isc vector(Ifl) until it touches the S.C.C curve at Point C and draw a vertical line from that point that touch the O.C.C curve at point B and find the value of Vph at this point(Point B)

i this possible in matlab ?

so far i was managed to draw the horizontal line but i'm unable to get the point where it touches the S.C.C curve.

any guidance would be appreciated.

Worked Exampe:

Ifl=288
Vph=[450;900;1150;1320]
If=[10;20;30;40]
Isc=[---;220;335;---]
*the dashed lines meanes that theres no registered value of Isc to the corresponding value of If.
Point C=(26.5,288) 
Vph at Pt B =1060

[dpb]

Sure, it's doable--just have to have a way to pick the first point. Ideally, if had a functional form for the two curves makes it simpler but can be done from datapoints only if must.

To help others help you, attach the data from which to make a working example...

[Okita Sugoo]

these are the data used in plotting the curves above.

[Okita Sugoo]

[dpb]

We can't do anything useful with images; attach the data as files and your code for starting point...

Answer 1

[dpb]

Actually, after looking at the drawings some more, I realize you did supply enough originally to make an initial pass at it...

Ifl=288;
Vph=[450;900;1150;1320];
If=[10;20;30;40];
Isc=[nan;220;335;nan];    % for missing data --> NaN
%Point C=(26.5,288) 

plot(If,Vph)
hold on,plot(If,Isc)
xlim([0 50]), ylim([0 1500])
% results in sorta' like the drawing plot...looks better if
IfInterp=linspace(If(1),If(end),50);           % more points to smooth curve
VphInterp=interp1(If,Vph,IfInterp,'pchip');    % use shape-keeping cubic piecewise poly
plot(IfInterp,VphInterp,'k-')                  % and show what that looks like...

C=interp1(Isc(2:3),If(2:3),Ifl)                % find intersection @ Ifl
C =
   25.9130
% result doesn't quite match your value...neighborhood but not actual intersection

% now look for intersection of Vph at C...
>> interp1(If,Vph,C)                          % linear interpolation
ans =
   1.0478e+03
>> format bank
>> ans
ans =
       1047.83
>> interp1(If,Vph,C,'pchip')                  % use the pchip interpolation
ans =
       1061.38
>> 

The last value is quite close to your estimate...

All you need to do is wrap the above in a function; drawing the horizontal and vertical lines on the plot shouldn't be difficult...as long as you stay within the relatively narrow limits of the SCC curve, it's simply a two-step interpolation process as outlined above.