How to find maximum amplitude of a vibration plot?

How do i find the maximum amplitude (Y value) and corresponding x-value for such plots?

Answer 1

[DGM]

Something like

% example data
x = linspace(0,2*pi,100);
y = sin(x);

[maxy idx] = max(y); % find maximal y-value
maxx = x(idx); % find corresponding x-value
[maxx maxy] % location of maximal point in the set

ans = 1×2

1.5867 0.9999

plot(x,y); hold on
plot(maxx,maxy,'o')