How to find x value for certain y value of a lineplot in matlab

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I want to get EV value at P=50% without real data point at P=0.5 in the lineplot.
  1 Comment
佳丽 周
佳丽 周 on 8 Jun 2022
EV=[-15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15]
P=[0.0312500000000000,0,0.0312500000000000,0.0156250000000000,0.00625000000000000,0.0208333333333333,0.0186011904761905,0.0429687500000000,0.0282118055555556,0.0312500000000000,0.0539772727272727,0.0758838383838384,0.130080856643357,0.158545100732601,0.256227106227106,0.439955357142857,0.648752289377290,0.705156822344322,0.740785256410257,0.809659090909091,0.869444444444444,0.903125000000000,0.912946428571429,0.949218750000000,0.971726190476191,0.989583333333333,0.987500000000000,0.992187500000000,0.968750000000000,1,1]

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Accepted Answer

Torsten
Torsten on 8 Jun 2022
EV = EV(5:14);
P = P(5:14);
EV_05 = interp1(P,EV,0.5)
  7 Comments
佳丽 周
佳丽 周 on 8 Jun 2022
Before posting online, I tried to fit a linear equation according to the nearest two data points. But I didn't get what I want proprely. May be chose a larger interval will be better fit my data.Thanks for your good explanation!

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More Answers (2)

SALAH ALRABEEI
SALAH ALRABEEI on 8 Jun 2022
You can find the the EV from the index of p value.
Example;
a=[4,2,3,5,6,7]
a = 1×6
4 2 3 5 6 7
b = a.^2
b = 1×6
16 4 9 25 36 49
Now, to find what is a at b= 9!
inx = find(b==9);
a(inx)
ans = 3
  2 Comments
Sam Chak
Sam Chak on 8 Jun 2022
If the specific data and governing equation are unavailable, then you can only rely on Interpolation and Approximation Theory to find out the value.
More importantly, can you furnish the 17 visible data points (EV, P) for one-step further investigation of your NaN result?

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Sam Chak
Sam Chak on 8 Jun 2022
No joke, but this is the graphical approach.
  2 Comments
Sam Chak
Sam Chak on 8 Jun 2022
Edited: Sam Chak on 8 Jun 2022
Cute? Vote if you think it is cute, but I guess you are probably cuter, Ms. Zhou 😊

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