full width at half maximum

Hello all I have a curve shape plot and Im using the codes below to find the two Xs associated with the y at half Max % halfMaxLeftIndex = find(y>=maxY/2, 1, 'first'); % halfMaxRightIndex = find(y>=maxY/2, 1, 'last')

gives me the error below

halfMaxLeftIndex =

   Empty matrix: 1-by-0

Could you please advise

thanks

Answer 1

[Adam]

Have you defined maxY somewhere?

An empty matrix is not an error, it just means that the find operation did not find any elements of the array meeting your criterion.

find( y >= max(y)/2, 1, 'first' );

should certainly never return an empty matrix but with your version, if maxY is undefined or incorrectly defined it might.