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loulou85

铜虫 (正式写手)

[交流] 【求助】matlab模拟公式

我想模拟附件中的公式,下面是我写的程序
clc
close all;
syms xi eta tau ;
a=1;
tau=1;
c=1500;
rho=1000;
N=100;
%t=[0:1:1];
x=0;
xi=300;
eta=300;
p1=zeros(N,1);    %采样点数
f=zeros(N,1);
%xi eta粘滞 rho密度 tau 脉宽
omega=sqrt(4*a^2*c.^2-a^4*((xi+(4*eta/3))/rho)^2);
  f(t)=tau*exp(-((t/pi).^2))/sqrt(pi);
  s(t)=diff(f)-((xi+(4*eta/3))/rho)*diff(f,2);
for t=1:N
    p1(t)=exp(-(a^2)*((xi+(4*eta/3))/rho)*t)*sin(omega*t-a*x)/(2*omega);
     p(t)=conv(p1(t),s(t));
end
plot(p)

报错如下
??? Error using ==> unknown
Matrix dimensions must agree.

Error in ==> viscosityl at 18
  s(t)=diff(f)-((xi+(4*eta/3))/rho)*diff(f,2);

请高手帮忙改正,谢谢
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loulou85

铜虫 (正式写手)

t=linspace(0,1,100);  这里的100是秒吧,我改成t=linspace(0,0.001,10);咋报错??? Attempted to access s(9); index out of bounds because numel(s)=8.

Error in ==> viscosity2 at 22
p(t)=p1(t)*s(t);
呢

改成t=linspace(0,0.1,10);也不行呀?

[ Last edited by loulou85 on 2009-4-25 at 15:51 ]
3楼2009-04-25 15:49:08
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hitzhang

木虫 (正式写手)

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woshilsh(金币+4,VIP+0):常来,吼吼 4-25 13:42
loulou85(金币+10,VIP+0): 4-25 15:43
>> a=1;
tau=1;
c=1500;
rho=1000;
N=100;
t=linspace(0,1,100);
x=0;
xi=300;
eta=300;
p1=zeros(N,1);    %采样点数
f=zeros(N,1);
%xi eta粘滞 rho密度 tau 脉宽
omega=sqrt(4*a^2*c.^2-a^4*((xi+(4*eta/3))/rho)^2);
f=tau*exp(-((t/pi).^2))/sqrt(pi);d1=diff(f);d2=diff(f,2);
s=d1(1end-1))-((xi+(4*eta/3))/rho)*d2;
for t=1N-2)
p1(t)=exp(-(a^2)*((xi+(4*eta/3))/rho)*t)*sin(omega*t-a*x)/(2*omega);
p(t)=p1(t)*s(t);
end
>> plot(p)
>>
2楼2009-04-25 12:36:47
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hitzhang

木虫 (正式写手)

★ ★ ★ ★ ★ ★
loulou85(金币+3,VIP+0): 4-26 11:06
loulou85(金币+1,VIP+0): 4-26 11:06
sunxiao(金币+2,VIP+0):谢谢参与,欢迎常来仿真编程版 4-26 23:52
t=linspace(0,1,100); %100的意思是从0到1等间距取100个点
4楼2009-04-25 19:06:52
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loulou85

铜虫 (正式写手)

大侠,再问一下,画出p的频域图怎么写呀?,横轴不知道怎么转换,谢谢
5楼2009-04-26 11:07:36
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