Matlab - create a table from a vector in the first row and another in the first column

Hello, I am trying to make a table inside Matlab, but it is not coming out with the correct results.

My routine:

alpha=0.008;
gamma=3.3;
g=9.80665; 
delta_1=0.07; % if f<=fp
delta_2=0.09; % if f>fp
Tp=2:16;   
fp=1./Tp;  
T=2:16;    
f=1./T;    
 nrows = 14;  
ncols = 14;
E = ones(nrows,ncols);
 
for fp = 1:ncols      
    for f = 1:nrows   
        if f<=fp
            E(f,fp) = (alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_1*fp))^2);
        elseif f>fp
            E(f,fp) = (alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_2*fp))^2);
        else
            E(f,fp) = 0;
        end
    end
end
E

Attached is a figure that is reality (as it turned out) and another as expectation (as it was meant to be).

I thank you for your help.

Answer 1

[Mathieu NOE]

hello

i noticed some mistakes regarding usage of f and fp : you have initialised as vectors of decimal scalars. Then later on, you use them as loop index , therefore overwritting the f and fp values as integers. I guess this was not the intention.

i could not get the expected result because I don't know how the reference (expected) data where generated. i miss this info.

What is sure, is that the row / columns where we expect to see 0 cannot be obtained with your matlab code. So there must be another error somewhere in the logic and / or in the equations.

if you could send me the math behind what you are trying to do, I could better help you.

FYI, this is how I modified your code in the first place

clc
clear all
%%%%%%%%%%

alpha=0.008;
gamma=3.3;
g=9.80665; 
delta_1=0.07; % if f<=fp
delta_2=0.09; % if f>fp

Tp=2:16;   
% fp=1./Tp;  
fp_vector=1./Tp;  % 
T=2:16;    
% f=1./T;    
f_vector=1./T;   

nrows = 14;  
ncols = 14;
E = ones(nrows,ncols);

% ?? f and fp cannot be at the same time used as vector of decimal scalars and index in a for loop
% see correction below
 
% for fp = 1:ncols      % fp loop
for cj = 1:ncols      % fp loop
%     for f = 1:nrows   % f loop
    for ci = 1:nrows   % f loop
        
        % extract f and fp  value
        f = f_vector(ci);
        fp = fp_vector(cj);
        
        if f<=fp
            E(ci,cj) = (alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_1*fp))^2);
        elseif f>fp
            E(ci,cj) = (alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_2*fp))^2);
        else
            E(ci,cj) = 0
            % this condition is never reached as all cases are already covered with the two conditions above
            % so what condition is supposed to give E = 0 ? 
        end
    end
end

E

[Jacqueline Rigatto]

Thank you so much for your help, Mathieu NOE.

[Mathieu NOE]

happy to have helped someone today !!