Loop with row and column difference (multiplication)

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Jacqueline Rigatto
Jacqueline Rigatto 2020-11-10
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
David Hill 2020-11-10
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');

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回答（2 个）

Cris LaPierre
Cris LaPierre 2020-11-10
Assuming you meant to include a Q2, I'd do this using cumprod instead of a for loop.
David Hill
David Hill 2020-11-10
编辑：David Hill 2020-11-10
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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Jacqueline Rigatto
Jacqueline Rigatto 2020-11-11
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;
Thank you for your help David Hill

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