# Homework Help: Histogram and Rayleigh distribuition

1. Oct 31, 2014

### Jay Sebi

1. The problem statement, all variables and given/known data
1. (iv) Calculatethehistogramforthewaveheightandwaveperiod.

2. (v) Compare the histogram with the Rayleigh distribution.

3. (vi) Calculate exceedance probability distribution for the wave height and wave period using plotting position formulae and compare it with Rayleigh distribution exceedance probability distribution.
I have in matlab this code that gives me the periods and wave height for each period.
code:
clc

clear all
filename = '/Users/helenapereira/Desktop/A1-Wave Data.txt';

delimiter = '\t';

startRow = 3;

formatSpec = '%f%f%[^\n\r]';

fileID = fopen(filename,'r');

dataArray = textscan(fileID, formatSpec, 'Delimiter', delimiter, 'HeaderLines' ,startRow-1, 'ReturnOnError', false);

fclose(fileID);

Time = dataArray{:, 1};

WAVE = dataArray{:, 2};

clearvars filenamedelimiterstartRowformatSpecfileIDdataArrayans;

%%%UPCROSS%%%

% Finding Zeros

ii=1;

for i=1:length(WAVE)-1

if and(WAVE(i)<0,WAVE(i+1)>0)

Indices(ii)=i;

ii=ii+1;

end

end

%Zero Crossing

for i=1:length(Indices)

ZeroCrossing(i)=interp1(WAVE(Indices(i):Indices(i)+1),Time(Indices(i):Indices(i)+1),0,'linear');

end

%Period

ii=1;

for i=1:length(ZeroCrossing)-1

Period(ii)=ZeroCrossing(i+1)-ZeroCrossing(i);

ii=ii+1;

end

%Wave Height

ii=1;

for i=1:length(Indices)-1

Wmax=max(WAVE(Indices(i):Indices(i+1)));

Wmin=min(WAVE(Indices(i):Indices(i+1)));

H(ii)=Wmax-Wmin;

ii=ii+1;

end

%Mean Wave Height

Hmed=mean(H);

%Mean Wave Period

Tmed=mean(Period);

%Hs and H1/10

sort(H,'descend');

a=ceil(length(H)/3);

b=ceil(length(H)/10);

Hs=mean(H(1:a));

Hdec=mean(H(1:b));

%Ts and T1/10

sort(Period,'descend');

c=ceil(length(Period)/3);

d=ceil(length(Period)/10);

Ts=mean(Period(1:c));

Tdec=mean(Period(1:d));

I now need to make the histograms.
however the function histfit gives me the error:
Undefined function 'histfit' for input arguments of
type 'double'.
2. Relevant equations
the histfit equation on matlab

3. The attempt at a solution
Use histfit equation to get the histogram and rayleigh distribuition.

2. Nov 5, 2014