findpeaks alternative - help fixing code

For my project i dont have access to findpeaks so need to make my own version. I have attempted to do this so that when input with frequency and relativePower up to 3 frequencies which occur at peak relativePower values are outputted.

( The sort function used works by sorting the first input into ascending order and then applying the same changes to the second input)

But currently I get errors when trying to run it.

I have attached values of frequency and relative power.

function [ThreeFrequencyPeaks] = PeakFind(frequency,relativePower)

rP = relativePower;

% If the nth value of rP is less than 0.1 delete the nth rP value and the
% nth frequency value.
for n=1:length(rP)
    if rP(n)<=0.1
        rP(n) = [];
        frequency(n) = [];
    end
end

% Check the rP value either side of the nth value of rP and if the nth
% value is bigger than both of them save the rP to powerPeaks and save the
% corresponding frequency to frequencyPeaks
for n= 2:length(rP)
    if rP(n) > rP(n-1) && rP(n)>rP(n+1)
        frequencyPeaks = frequency(n);
        powerPeaks = rP(n);
    else
    end
end

% Sort frequencyPeaks with respect to powerPeaks using my function
[~, FrequencyPeaks] = mysortdata(powerPeaks, frequencyPeaks);

% Flip FrequencyPekas so that it goes biggest to smallest
FrequencyPeaksFliped = fliplr(FrequencyPeaks);

if length(t) > 3
    ThreeFrequencyPeaks = FrequencyPeaksFliped(1:3);
elseif length == 2
    ThreeFrequencyPeaks = FrequencyPeaksFliped(1:2);
else
    ThreeFrequencyPeaks = FrequencyPeaksFliped(1);

end
end

function [time, signal] = mysortdata(time, signal)
% Make sure we have data to sort
if numel(time) <= 1
  return
end
% Define points of where to split the vectors
PivotTime = time(end);
PivotSignal = signal(end);
%Remove this point from vecotr
time(end) = [];
signal(end) = [];

less     = (time <= PivotTime);
%  input Less and More into this function again 
[LessTime, LessSignal] = mysortdata(time(less), signal(less));
[MoreTime, MoreSignal] = mysortdata(time(~less), signal(~less));

% Put vectors back together
time  = [LessTime, PivotTime, MoreTime];
signal = [LessSignal, PivotSignal, MoreSignal];
end

[Bruno Luong]

May be you forget, but a friendly reminder: if you use the code published in this Answer as showed above you might want to acknowdledge it.

Answer 1

[Sean de Wolski]

How about: islocalmin and islocalmax?