How can i know the abscissa of the maximum of a curve ?

Hi

I have a curve Amplitude=f(frequency) and i want to know the abscissa of the maximum.

Please help me.

[Adam]

Isn't the abscissa just the y-axis value of your function - i.e. Amplitude?

So just run your function and call

max( Amplitiude )

on the result.

[John D'Errico]

Adam - Sorry, but no. Back to grade school for this.

https://en.wikipedia.org/wiki/Abscissa

The y axis is the ordinate, not the abscissa.

Answer 1

[John D'Errico]

So you have a function of a single variable, and you need to know the location of the min.

If you have the function itself, then use fminbnd.

If you have only data points, thus (x,y) pairs, then use min. It returns the index of the minimum value(look at the second output argument), then use that index on the vector of x values.

If you want to find a minimum on data points, but you need an interpolated minimum, then you can use fminbnd on a spline fit. Don't expect it to be very good though.