Loop with row and column difference (multiplication)

Question

Jacqueline Rigatto 2020-11-10

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/643540-loop-with-row-and-column-difference-multiplication

评论： Jacqueline Rigatto 2020-11-12

I would like to know how I do a loop multiplying Q1 with O3 (result in Q3). Then multiply Q3 with O4 and so on for each column.

I tried to explain with other software to facilitate understanding. Thank you for your help.

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David Hill 2020-11-10

在 MATLAB Online 中打开

Did you look at my answer? First load your file and look at the data to see how it was loaded (how it is named). It would help if you attached your data file.

load('yourfile');

Jacqueline Rigatto 2020-11-10

A2.m

My script

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Answer 1

Cris LaPierre 2020-11-10

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https://ww2.mathworks.cn/matlabcentral/answers/643540-loop-with-row-and-column-difference-multiplication#answer_540465

Assuming you meant to include a Q2, I'd do this using cumprod instead of a for loop.

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Jacqueline Rigatto 2020-11-12

Thank you for your help Cris LaPierre

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Answer 2

David Hill 2020-11-10

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https://ww2.mathworks.cn/matlabcentral/answers/643540-loop-with-row-and-column-difference-multiplication#answer_540470

编辑：David Hill 2020-11-10

在 MATLAB Online 中打开

I assume your arrays when imported will start at 1. Looks like you just want cumprod() of O times initial Q.

Q(2:end)=Q(1)*cumprod(O);

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David Hill 2020-11-10

在 MATLAB Online 中打开

clear all; clc; close all
alpha=0.008;
gamma=3.3;
g=9.8; 
delta_1=0.07; 
delta_2=0.09; % if f>fp
Tp=[2 8 16];   
freq_p=1./Tp;  
i_freq=1:69;
f1=0.03093;  
c=1.1;
for i = 1:length(i_freq)
fi=f1.*c.^(i_freq-1);
end
 
freq_fi=fi;    
nrows = length(freq_fi); 
ncols = length(freq_p);
E = ones(nrows,ncols);
fc = 0.4054;  % [rad/s]
for i = 1:nrows            
    for j = 1:ncols      
        
        f = freq_fi(i);
        fp = freq_p(j);
        
        if f<fc 
            if f<=fp
            E(i,j) = (alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_1*fp))^2);
            else
            E(i,j) = (alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_2*fp))^2);
            end
        elseif f>fc
           if f<=fp
            E(i,j) = (fc/f)^5*(alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_1*fp))^2);
           else
            E(i,j) = (fc/f)^5*(alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_2*fp))^2);
           end
        else
            E(i,j)=0;
        end
    end
end
     
E;
%%%  Dir(teta)
i_teta=1:36;
teta_i=10.*i_teta;
teta_i_cos=cos(2*teta_i);
for i = 1:length(teta_i_cos)
 if teta_i_cos>0
    dir_teta=0;
else
    dir_teta= (2/pi())*(1/2)*(1+teta_i_cos);%cos^2(x) = (1+cos2x)/2
end 
end
dir_teta;
f_teta=teta_i;
%%%%%%%%%%%%% My  problem below %%%%%%%%%%%%%%%%%%%%
%%% T=2s
T2=E(:,1);
T2(T2==0)=1;%changed all T2 values that were 0 to 1 (if you multiply by zero everything below will be zero)
%when I ran it without this, the whole 69x36 matrix was zeros
aux_T2=cumprod(T2)*dir_teta;

Jacqueline Rigatto 2020-11-11

在 MATLAB Online 中打开

I managed to do it using the code:

clear all; clc; close all
alpha=0.008;
gamma=3.3;
g=9.8; 
delta_1=0.07; 
delta_2=0.09; % if f>fp
Tp=[2 8 16];   
freq_p=1./Tp;  
i_freq=1:69;
f1=0.03093;  
c=1.1;
for i = 1:length(i_freq)
fi=f1.*c.^(i_freq-1);
end
 
freq_fi=fi;    
nrows = length(freq_fi); 
ncols = length(freq_p);
E = ones(nrows,ncols);
fc = 0.4054;  % [rad/s]
for i = 1:nrows            
    for j = 1:ncols      
        
        f = freq_fi(i);
        fp = freq_p(j);
        
        if f<fc 
            if f<=fp
            E(i,j) = (alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_1*fp))^2);
            else
            E(i,j) = (alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_2*fp))^2);
            end
        elseif f>fc
           if f<=fp
            E(i,j) = (fc/f)^5*(alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_1*fp))^2);
           else
            E(i,j) = (fc/f)^5*(alpha*(g^2)*((2*pi)^(-4))*(f^(-5)))*exp((-5/4)*((f/fp)^(-4)))*gamma*exp((-1/2)*((f-fp)/(delta_2*fp))^2);
           end
        else
            E(i,j)=0;
        end
    end
end
     
E;
%%%  Dir(teta)
i_teta=1:36;
teta_i=10.*i_teta;
teta_i_cos=cos(2*teta_i);
for i = 1:length(teta_i_cos)
 if teta_i_cos>0
    dir_teta=0;
else
    dir_teta= (2/pi())*(1/2)*(1+teta_i_cos);%cos^2(x) = (1+cos2x)/2
end 
end
dir_teta;
f_teta=teta_i;
%%%%%%%%%%%%% My  problem below %%%%%%%%%%%%%%%%%%%%
%%% T=2s
T2=E(:,1);
T2=T2';
aux1=cumprod(dir_teta');
aux2=repmat(aux1,1,69);
aux3=aux2.*T2;