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how can i plot this equation ??? please

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sihem chaib
sihem chaib 2014-2-15
评论： sihem chaib 2014-2-15
clear all
clc
%le 29/10/2013 à 23h00
%les géométries de la poutre
M=30; % masse de la poutre KG/ML??
EI=200*10^7;% Rigidité flexionnelle de la poutre N/m^2
%l=22;%m
%les caractéristiques du sol
c=0;% constante d'amortissement
k=0.2*10^8;% rigidité du sol N/m^2
v=5;%vitesse m/s de chargement
n1=5;%nombre des modes
%longueur de la poutre en m
l=(3*pi/2)*(4*EI/k)^0.25; %m;
%les conditions initiales
v_0=0;%m/s;vitesse initiale
T_0=0.01*10^-4;%m déplacement initial
t1=l/v;
for m=1:n1;
x=1:0.01:l+1;
phi(x,m)=sin((x-1)*pi*m/l);
t=1:0.01/v:t1;
beta=c/(2*M);
B=T_0;
w_d(m)=((((m^4)*(pi^4)*EI)/(M*(l^4)))+(k/M))^0.5; %pulsation propre
w_n(m)=((w_d(m)^2)-(beta^2))^0.5;% pseudo pulsation
A(m)=((v_0)+(B*beta))/w_n(m);
T(t,m)=(exp(-beta*(t-1)*(A(m)*sin((w_n(m))*(t-1))+B*cos((w_n(m))*(t-1)))));
ww(x,t,m)=phi(x,m)*T(t,m);%(sin(m*pi*(xx1(i)-1)/l))* T(j,m);%((exp(-beta*(tt1(j)-1)))*(A(m)*sin((w_n(m))*(tt1(j)-1))+B*cos((w_n(m))*(tt1(j)-1))));
end
x=1:0.01:l+1;
t=1:0.01/v:t1;
ww1(x,t)=0;
for m=1:n1;
ww1(x,t)=ww1(x,t)+ww(x,t,m);
end
plot (ww1(:,1),'B');
hold on
%remarque : se sont des ondes stationaires changent d'emplitudes mais ne
%changent pas de position.
  2 个评论
Walter Roberson
Walter Roberson 2014-2-15
编辑：Walter Roberson 2014-2-15
Side note: you can replace
ww1(x,t)=0;
for m=1:n1;
ww1(x,t)=ww1(x,t)+ww(x,t,m);
end
with
ww1(x,t) = sum(ww(x,t,:));
sihem chaib
sihem chaib 2014-2-15
ok think you i try your proposition

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采纳的回答

Walter Roberson
Walter Roberson 2014-2-15
Your code has
t=1:0.01/v:t1;
ww1(x,t)=0;
so you are trying to use t as an index into an array. But t has values like 1.80 and floating point numbers cannot be used as indices.
Try
t=1:0.01/v:t1;
ww1(x, 1:length(t)) = 0;
Except, that is, that as I noted above you do not need to initialize ww1(x,t). So you can take the statement I gave
ww1(x,t) = sum(ww(x,t,:));
and replace it with
ww1(x,1:length(t)) = sum(ww(x,1:length(t),:),3);

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