interp1 function knowing X coordinates

Hello everybody ;

so here I have twwo equations FX and FY as shown in the figure

>>

with intersections points . with the function inter1 , and by putting the the equations : FZ=FX-FY , I found the intersection points but only the xx' coordinates.

I wonder if there is a quick method to get the yy' coordinates while knowing the xx' coordinates .

my problem is more complicated than that but this the general idea. how to know the yy' coordinates by knowing the xx' coordinates of the intersection points.

2 - as you can see also by the same figure, plot gives you the hand to know the coordinates of each point on the graph , so is there any possibility to get these points by this way ?

thank you

[Stephen23]

Assuming that FX and FY are functions of x, then surely:

 FX(xx)
 FY(xx)

will both give the yy values at the intersection points xx (which apparently are known: "knowing the xx").

[heir ancestors]

thank you for your answer Stephen, but in this case it will give an empty matrix, because the values of xx are interpolated .

[Adam]

Why doesn't interp1 give you the y-value?

yy = interp1( x, y, xx )

[heir ancestors]

Hello adam,thank you for the answer , yes in fact I did that to obtain yy values , like the first and the seconf for the yy values, but the values given are not very exact. so I wanted to know if there is any other way to get them.

[Adam]

Not exact in what way? They are interpolated values at the x point you give which is, presumably, somewhere between two actual samples of x.

So unless you have the analytical function there is no 'true' value between those that you have defined discretely. There are various different interpolation methods, but which is best depends on the situation. All of them will give an approximation of the data value, they can't no the absolute correct value.