matlab, how do i write a statement that will give me time on xaxis from y=0.3

Question

x=[0:.01:10];
y=(x.^2).*(exp(-x));

plot(x,y), grid
y1=max(y);

xlabel(\'TIME\');
ylabel(\'CONCENTRATION IN BLOOD\');
title(\'CONCENTRATIN OF SUSTANCE IN BLOOD vs TI         


        

Answer 1

An easier way to find the index (and therefore x-value) is:

[minDiff, index] = min(abs(y-0.3))

minDiff =

  3.9435e-004


index =

    84

 x(index)

ans =

    0.8300