how to find a certain coordinate value in a curve

Hi everyone, i need help.

Suppose i have a curve data as i attached. How do i find a B value that correspond to certain A value from that curve?

 %%IMPORT OUTPUT FILE INTO MATLAB
load 'data.txt'
X=data(:,1);
Y=data(:,2);
A=max(X);
B=??

thanks for your help!

Answer 1

[Star Strider]

Ask the max function for two outputs. The second is the index of the first occurrence of the maximum in your vector, and use the index to define the corresponding value of ‘y’:

[A,idx] = max(X);
B = y(idx);