how to find the bottom peaks in the graph?

how to find decreasing order of peaks in graphs, so that how much graphs goes deeper at higher frequencies (plz refer image.).i have to find the values so that my graph reaches as deeper as possible at higher frequency.

[KSSV]

REad about findpeaks

[Sun Heat]

bottom peaks not top peaks of the image file

[Thumree Sarkar]

data= - data, then use findpeaks, you will get the bottom peaks.

Answer 1

[madhan ravi]

[locs,idxs]=findpeaks(-y) %EDITED

If y is the function of the plot -y will give the minimum of the function.

[Sun Heat]

i want multiple peaks but it gives only 64 at 700Mhz. It should also give -36 at 150MHz and many more.

[madhan ravi]

Check the edited code now.

Answer 2

[Image Analyst]

Find valleys by sending the inverted vector into findpeaks() and finding the peaks. Then you have to invert again to get the positive values (since you have inverted/negated it):

% Find values and locations:
[negPeakValues, indexesOfValleys] = findpeaks(-signal);
% Invert values to get the original, non-inverted values.
valleyValues = -negPeakValues;

Answer 3

[Jim Riggs]

Here is a similar problem. To find the bottom peaks, just change one line from

if(D(i) >0 && D(i+1)<0

to

if(D(i)<0 && D(i+1)>0

https://www.mathworks.com/matlabcentral/answers/420050-comparing-consecutively-numbers-to-find-the-peaks-of-a-function#answer_337668?s_tid=prof_contriblnk