In an assignment A(I) = B, the number of elements in B and I must be the same.

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butz] 2015-7-1

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https://ww2.mathworks.cn/matlabcentral/answers/226401-in-an-assignment-a-i-b-the-number-of-elements-in-b-and-i-must-be-the-same

评论： butz] 2015-7-1

采纳的回答： Azzi Abdelmalek

在 MATLAB Online 中打开

I have a problem with my current Matlab code

if true
  % code
end
if true
  Nt=T/dt+1;
t=0:dt:T;
phi=zeros(Nt,1);
b=zeros(Nt,1);
f=zeros(Nt,1);
p(1)=3;
b(1)=10;
f(1)=l;
for i=1:Nt-1
b(i)=(12*pi(i))/(2*r)^2;
f(i)=l*p(i)^(3/2)/(2*r^2*((p(i)-1)^(1/2)));
p(i+1)=p(i)+dt*(p(i)-p(i)*((1-f/(sqrt(b*p(i))*x))*sinh(sqrt(b*p(i))*x)));
end

For p(i+1) Matlab keeps saying "In an assignment A(I) = B, the number of elements in B and I must be the same." Any ideas?

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Adam 2015-7-1

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You can use syntax like:

p(i+1,:) = ...

to enter values into a 2d array whose second dimension can be 601, but this only works if every set of results being entered into the array has size 601 which is not the case because you assign:

p(1) = 3;

at the start and I don't know if your results are the same size every time round the loop either.

butz] 2015-7-1

编辑：butz] 2015-7-1

在 MATLAB Online 中打开

if true
clear all 
clc
l=1;
r=1*10^-6;                                                                                                                                    
x=2;                                          
dt=0.005;                                       
T=3;  
Nt=T/dt+1;
t=0:dt:T;
p=zeros(Nt,1);
b=zeros(Nt,1);
f=zeros(Nt,1);
p(1)=3;
b(1)=10;
f(1)=l;
for i=1:Nt-1
b(i)=(12*p(i))/(2*r)^2;
f(i)=l*p(i)^(3/2)/(2*r^2*((p(i)-1)^(1/2)));
p(i+1)=p(i)+dt*(p(i)-p(i)*((1-f/(sqrt(b*p(i))*x))*sinh(sqrt(b*p(i))*x)));
end

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采纳的回答

Azzi Abdelmalek 2015-7-1

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/226401-in-an-assignment-a-i-b-the-number-of-elements-in-b-and-i-must-be-the-same#answer_184717

在 MATLAB Online 中打开

Nt=T/dt+1;
t=0:dt:T;
phi=zeros(Nt,1);
b=zeros(Nt,1);
f=zeros(Nt,1);
p(1)=3;
b(1)=10;
f(1)=l;
for i=1:Nt-1
  b(i)=(12*p(i))/(2*r)^2;
  f(i)=l*p(i)^(3/2)/(2*r^2*((p(i)-1)^(1/2)));
  p(i+1)=p(i)+dt*(p(i)-p(i)*((1-f(i)/(sqrt(b*p(i))*x))*sinh(sqrt(b*p(i))*x)));
end