How to find a y value for a given x in a plot?

I have plotted a curve with a given dataset. Now I want to find the value of y for a certain value of x. The code and graph is give below.

filen='argo-profiles-2902294.nc'

p=ncread(filen,'PRES');
t=ncread(filen,'TEMP');

p1=p(:,2)
t1=t(:,2)

plot(t1,p1,'k')
set(gca,'YDir','reverse')

Now, let's say I want to find the pressure value for a certain x value (say 25). What to do?

Answer 1

[Chunru]

x1 = 25;
y1 = interp1(t1, p1, x1);

[Anirban Mandal]

I have tried that already but matlab was giving me an error. The code and error is given below

clc
clear all

filen='argo-profiles-2902294.nc'

p=ncread(filen,'PRES');
t=ncread(filen,'TEMP');

p1=p(:,2)
t1=t(:,2)

plot(t1,p1,'k')
set(gca,'YDir','reverse')

p2=interp1(t1,p1,20)

[Chunru]

Can you post your data t1 and p1?

[Anirban Mandal]

Here it is

[Chunru]

p1 = readmatrix("p1.xlsx");
t1 = readmatrix("t1.xlsx");
whos

  Name        Size            Bytes  Class     Attributes

  ans         1x32               64  char                
  p1        970x1              7760  double              
  t1        970x1              7760  double              

% Your data has nan
p1(end-10:end)

ans = 11×1

NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN

% Remove the nan first
idx = any(isnan([t1 p1]), 2);
t1(idx) = []; p1(idx)= [];

p2=interp1(t1,p1,20)

p2 = 92.7622

[Anirban Mandal]

Okay