Help modifying a User-defined-function

I am trying to compute the mean max and mean min amplitude of time series datasets. These timeseries are arranged in each column of a matrix, so that the matrix is 351x117 . So 117 timeseries. I have found a user defined function that can do just that.The problem is that this UDF is meant for only 1 timeseries array at a time, x. How can I modify the following UDF to accomodate for a matrix,A, instead of an array x. Note that the desired output will be in temp78. I will need to compute the average of the fist two columns of temp78 in order to find the avg max and min amplitudes for every timeseries.

[Walter Roberson]

It is easier for us to work with code than with a picture of code.

[Vivek]

Here is it. Any help is much appreciated.

% OUTPUT
% temp80 gives sorted wave height and corresponding period
% temp78 gives raw upcrossing info.
% NT is the number of waves
%
% INPUT
% x is the time series of interest
% N is length of time series
% dt is 1/(sampling frequency)
%---------------------------------------------------------------------


function [temp80,temp78,NT]=zero_cross(x,N,dt)

% find zero-crossing points
   temp70 = x(1:N-1).*x(2:N);
   temp70(N) = 1.0;
   temp72=find(temp70<0);

   temp73 = zeros(N,1);
   temp74 = zeros(N,1);
   temp75 = find(x<0);
   temp73(temp72) = 1;
   temp74(temp75) = 1;
   temp76 = and(temp73,temp74);
   temp77 = find(temp76>0);
   temp555 = temp77/24;
   temp78 = zeros(N,4);

% total number of complete waves
   NT = sum(temp76)-1;

% find local maxima, minima, duration and occurance
%   Hmax Hmin Tdur Tocur
   for i = 1:NT;
      temp78(temp77(i),1)  = max(x(temp77(i):temp77(i+1)));
      temp78(temp77(i),2)  = min(x(temp77(i):temp77(i+1)));
      temp78(temp77(i),3)  = temp77(i+1) - temp77(i);
      temp78(temp77(i),4)  = temp77(i);
   end
   
   %output
   temp78=temp78(find(temp78(:,4)>0),:);    %raw upcrossing data
   temp79(:,1)=temp78(:,1)-temp78(:,2);     %wave height
   temp79(:,2)=temp78(:,3)*dt;              %wave period
   temp80=flipud(sortrows(temp79,1));       %sorted H and T

Answer 1

[Ameer Hamza]

try something like the following code. Save this in a single file named zero_cross.m

function [temp80,temp78,NT]=zero_cross(x,N,dt)
    m = size(x,2); % num columns
    temp80 = cell(1,m);
    temp78 = cell(1,m);
    NT = cell(1,m);
    for i=1:m
        [temp80{i}, temp78{i}, NT{i}] = zero_cross1(x(:,i), N, dt);
    end
end

function [temp80,temp78,NT]=zero_cross1(x,N,dt)
% find zero-crossing points
   temp70 = x(1:N-1).*x(2:N);
   temp70(N) = 1.0;
   temp72=find(temp70<0);
   temp73 = zeros(N,1);
   temp74 = zeros(N,1);
   temp75 = find(x<0);
   temp73(temp72) = 1;
   temp74(temp75) = 1;
   temp76 = and(temp73,temp74);
   temp77 = find(temp76>0);
   temp555 = temp77/24;
   temp78 = zeros(N,4);
% total number of complete waves
   NT = sum(temp76)-1;
% find local maxima, minima, duration and occurance
%   Hmax Hmin Tdur Tocur
   for i = 1:NT;
      temp78(temp77(i),1)  = max(x(temp77(i):temp77(i+1)));
      temp78(temp77(i),2)  = min(x(temp77(i):temp77(i+1)));
      temp78(temp77(i),3)  = temp77(i+1) - temp77(i);
      temp78(temp77(i),4)  = temp77(i);
   end
   
   %output
   temp78=temp78(find(temp78(:,4)>0),:);    %raw upcrossing data
   temp79(:,1)=temp78(:,1)-temp78(:,2);     %wave height
   temp79(:,2)=temp78(:,3)*dt;              %wave period
   temp80=flipud(sortrows(temp79,1));       %sorted H and T
end

[Vivek]

This works! Thanks

[Ameer Hamza]

Glad to be of help.